Mammal Species of the World
- Original description: Linnaeus, C., 1758. Systema Naturae per regna tria naturae, secundum classis, ordines, genera, species cum characteribus, differentiis, synonymis, locis. 1:76.Tenth Edition, Vol. 1. Laurentii Salvii, Stockholm, 824 pp.
- somewhat laterally compressed
- sides of the body have a wrinkled appearance
- a thick, rounded, low dorsal hump
- followed by a series of crenulations which run the length of the tail stock
- pectoral flippers are wide and spatulate in shape
- tail flukes are
- with a comparatively straight trailing edge
- caudal peduncle is deep
- often a post-anal keel (Jefferson et al, 2008)
- colour ranges from black to dark blue-grey to pale grey.
- most animals have white colouration around the
- ano-genital region (Jefferson et al, 2008)
- Males may become much paler with age
- most animals have white colouration around the
- one-quarter to one-third the total body length (Jefferson et al, 2008)
- squarish in side profile
- generally smooth
- single S-shaped blowhole located on the left at the front of the head
- shape of the head is determined by the presence of the spermaceti organ
- which may contain up to 1900 litres of waxy oil
- exact function not fully understood it may
- assist in evacuating the lungs and absorbing nitrogen at extreme pressures
- regulate buoyancy during deep diving
- reverberate and focus sounds (Nowak, 2003)
- lower jaw is exceptionally narrow
- shorter than the upper jaw
- contains 18 to 26 pairs of conical, functional teeth
- teeth of the lower jaw insert into sockets in the soft tissue of the upper jaw
- upper jaw may possess small, vestigial teeth, but these remain buried in the soft tissue
Sexual dimorphism is extreme in sperm whales:
- Adult males may be over 18 metres in length, whilst females are up to 12 metres (Jefferson et al, 2008).
- Physically mature males may weigh between 35,000 and 50,000 kg, with females weighing around one-third as much (Nowak, 2003).
Longevity of sperm whales has been studied using tooth-sections. Dentinal growth layers are counted to determine age, with some animals estimated to be up to 70 years old (Rice, 1989). Females are thought to live longer than males (Ralls et al, 1980).
Females reach sexual maturity at around age 9 years, whilst males may be as old as 20 years before they become sexually active (Best, 2007). Gestation has been calculated variously at 14 to 19 months (Nowak, 2003). During the breeding season, mixed age and sex schools of sperm whales are joined by large, older males. These schools then become known as harem schools, with one adult male for every ten adult females (Nowak, 2003).
Sperm whales are a top predator. However, they may sometimes be attacked by killer whales and other odontocetes (Jefferson et al, 2008). Tablespoon-sized scoop marks and oval scarring on the back and flanks of sperm whales are evidence of attack by small sharks such as the cookie-cutter shark Isistius (Best, 2007). Other extensive scarring often found on the head and body may represent interactions with giant squid or other sperm whales.
Sperm whales are found throughout the world's oceans in deep waters to the edge of the ice at both poles (Waring et al. 2009 and references therein).
According to Waring et al. (2009), results of multi-disciplinary research conducted in the Gulf of Mexico during the first decade of the 21st Century confirm speculation that Gulf of Mexico Sperm Whales constitute a stock that is distinct from other Atlantic Ocean stocks(s). Sperm whales were commercially hunted in the Gulf of Mexico by American whalers from sailing vessels until the early 1900s. In the northern Gulf of Mexico (i.e., U.S. Gulf of Mexico), systematic aerial and ship surveys indicate that sperm whales inhabit continental slope and oceanic waters, where they are widely distributed. Seasonal aerial surveys confirm that sperm whales are present in at least the northern Gulf of Mexico in all seasons. The best available estimates indicate a population of around 1,500 Sperm Whales in the northern Gulf of Mexico. (Waring et al. 2009 and references therein)
Distribution in Egypt
- Keller, R.W., S. Leatherwood & S.J. Holt (1982). Indian Ocean Cetacean Survey, Seychelle Islands, April to June 1980. Rep. Int. Whal. Commn 32, 503-513. http://www.marinespecies.org/aphia.php?p=sourcedetails&id=6208
- Jan Haelters http://www.marinespecies.org/aphia.php?p=sourcedetails&id=141792
- Gordon, D. (Ed.) (2009). New Zealand Inventory of Biodiversity. Volume One: Kingdom Animalia. 584 pp http://www.marinespecies.org/porifera/porifera.php?p=sourcedetails&id=145244
- Felder, D.L. and D.K. Camp (eds.), Gulf of Mexico–Origins, Waters, and Biota. Biodiversity. Texas A&M Press, College Station, Texas. http://www.marinespecies.org/porifera/porifera.php?p=sourcedetails&id=145245
- van der Land, J. (2001). Tetrapoda, in: Costello, M.J. et al. (Ed.) (2001). European register of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification. Collection Patrimoines Naturels, 50: pp. 375-376 http://www.marinespecies.org/aphia.php?p=sourcedetails&id=1406
- Vanhaelen, M.-Th. (1989). Some observations on the beach between Koksijde and Oostduinkerke during and after the warm summer of 1989 [Enkele waarnemingen van het strand tussen Koksijde en Oostduinkerke tijdens en na de warme zomer van 1989]. De Strandvlo 9(4): 117-120 http://www.marinespecies.org/mollusca/aphia.php?p=sourcedetails&id=138706
- Slijper, E.J. (1938). Die Sammlung rezenter Cetacea des Musée Royal d'Histoire Naturelle de Belgique [The collection of recent Cetacea of the Musée Royal d'Histoire Naturelle de Belgique]. Bull. Mus. royal d'Hist. Nat. Belg./Med. Kon. Natuurhist. Mus. Belg. 14(10): 1-33 http://www.marinespecies.org/cetacea/aphia.php?p=sourcedetails&id=1619
- Borges, P.A.V., Costa, A., Cunha, R., Gabriel, R., Gonçalves, V., Martins, A.F., Melo, I., Parente, M., Raposeiro, P., Rodrigues, P., Santos, R.S., Silva, L., Vieira, P. & Vieira, V. (Eds.) (2010). A list of the terrestrial and marine biota from the Azores. Princípia, Oeiras, 432 pp. http://www.marinespecies.org/ascidiacea/aphia.php?p=sourcedetails&id=149079
- Koukouras, Athanasios. (2010). Check-list of marine species from Greece. Aristotle University of Thessaloniki. Assembled in the framework of the EU FP7 PESI project. http://www.marinespecies.org/asteroidea/aphia.php?p=sourcedetails&id=142068
- Lesage, Veronique, Jean-Francois Gosselin, Mike Hammill, Michael C.S. Kingsley, Jack Lawson (2007). Ecologically and Biologically Significant Areas (EBSAs) in the Estuary and Gulf of St. Lawrence - A marine mammal perspective. DFO Can. Sci. Advis. Sec. Res. Doc. 2007/046: 1-96. http://www.marinespecies.org/cetacea/aphia.php?p=sourcedetails&id=151497
- Gannier, A. (2000). Distribution of cetaceans off Society Islands (French Polynesia) as obtained from dedicated survey Aquat. Mamm. 26(2): 111-126. http://www.marinespecies.org/cetacea/aphia.php?p=sourcedetails&id=163031
Sperm whales roam the deep waters of all the oceans, though they seldom approach polar ice fields and are most common in temperate and tropical latitudes. They have also be seen occasionally near coastlines in the Gulf of Mexico, where they were once quite common.
Biogeographic Regions: arctic ocean (Native ); indian ocean (Native ); atlantic ocean (Native ); pacific ocean (Native )
- UNESCO-IOC Register of Marine Organisms http://www.marinespecies.org/aphia.php?p=sourcedetails&id=1318
occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Year-round
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) Throughout the world's oceans; adult females and young generally stay between 40 degrees north and 40 degrees south latitude. Nonbreeding males range into high latitude waters. Northern and southern hemisphere populations apparently are reproductively isolated from each other. See IUCN (1991) for further details.
WorldwideThe sperm whale is found in all oceans and adjoining seas except polar ice fields (Rice, 1977). Generally, only large, older males venture to the extreme northern and southern portions of the range, pole-ward of about 40-50 degrees latitude (Jefferson et al, 2008).
The most recent assessment of abundance using ‘best estimate’ model parameters puts the total global population of sperm whales at around 360,000 (Whitehead, 2002).
- IUCN Red Book, NMFS/NOAA Technical Memo
Above weights are given for mature male giant sperm whales. Females only weigh about 1/3 as much as males. Males may reach 19 m while females are only 12 meters. Newborn calves measure about 4 m and are about 1/25 the weight of females.
The enormous (up to 1/3 of total body length), box-like head of Physeter catodon sets it apart from all other species. The head contains a spermaceti organ whose function is not entirely known. It may serve to focus and reflect sound or may be a cooling organ to diminish the whale's volume and its buoyancy during prolonged dives. The giant sperm whale has the largest of mammalian brains in terms of sheer mass (approximately 9 kg). The blowhole slit is S-shaped and positioned on the left side of the head. There are 18-28 functional teeth on each side of the lower jaws, but the upper teeth are few, weak and nonfunctional. The lower teeth fit into sockets in the upper jaw. The gullet of Physeter catodon is the largest among cetaceans; it is in fact the only gullet large enough to swallow a human.
The dorsal fin is replaced by a hump and by a series of longitudinal ridges on the posterior part of the back, and the pectoral fins are quite small, approximately 200 cm. long. Tail flukes are 400-450 cm. The blubber layer of the giant sperm whale is quite thick, up to 35 cm. With respect to coloration, males often become paler and sometimes piebald with age. Both sexes have white in the genital and anal regions and on the lower jaws.
Range mass: 35000 to 50000 kg.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
Length: 1830 cm
Weight: 4.8E7 grams
- IUCN Red Book, NMFS/NOAA Technical Memo
Size in North America
Range: 11.0-18.3 m males; 8.3-12.5 m females
Range: 11,000-57,000 kg males; 6,800-24,000 kg females
Habitat and Ecology
The sperm whale is an animal of extremes in size (up to 18 m), sexual dimorphism (mature males have three times the mass of mature females), ecological imprint (sperm whales take roughly the same amount of biomass from the oceans as humans), and many other attributes (Whitehead 2003). The commercial value of the animal (a function of its size and the quality of sperm whale oil) drove two massive worldwide hunts: the technologically primitive “open-boat” hunt from 1712-~1920 (Starbuck 1878; Best 1983), and modern whaling using engine-driven whaling ships and harpoon guns from ~1910-1988 (Tonnessen and Johnsen 1982). The complex social structure of sperm whales may have been affected by whaling, lowering potential population growth rates, which are very low anyway (Whitehead 2003). On the positive side, sperm whales are very widely distributed (see above), and their primary prey, deep-water squid, are not yet major targets of fisheries.
The generation time (mean age of mothers) for sperm whales can be calculated if one assumes a set of population parameters, specifically age at first birth, mortality rate of mature females, and reproductive rate of mature females. There is uncertainty about these parameters, so two calculations were made using different assumptions:
a) Applying the population parameters most recently used for sperm whales by the International Whaling Commission’s Scientific Committee (International Whaling Commission 1982): age at first birth = 10 years; female reproductive rate in unexploited population = 0.20/year; female adult mortality = 0.055/yr): generation time = 27.3 years.
b) The estimates of mortality used by the International Whaling Commission are particularly problematic, and sperm whales likely have age-specific survival and reproductive rates. Thus it may be more realistic (Whitehead 2002) to use the well-established mortality schedule of killer whales (Orcinus orca; Olesiuk et al. 1990) and an age-specific pregnancy rate taken from the sperm whale data presented by Best et al. (1984; pregnancy rate for mature females = 0.257-0.0038xAge in years): generation time = 27.5
Sperm whales swim through deep waters to depths of 2 miles, apparently limited in depth only by the time it takes to swim down and back to the surface. Their distributions are depend upon season and sexual/social status, however they are most likely to be found in waters inhabited by squid- at least 1,000 m deep and with cold-water upswellings. Because they are so well-adapted for deep water swimming, they are in real danger of stranding when they move inshore.
Aquatic Biomes: benthic
- UNESCO-IOC Register of Marine Organisms http://www.marinespecies.org/aphia.php?p=sourcedetails&id=1318
Water temperature and chemistry ranges based on 2973 samples.
Depth range (m): 0 - 0
Temperature range (°C): -0.849 - 29.546
Nitrate (umol/L): 0.008 - 26.054
Salinity (PPS): 30.381 - 37.431
Oxygen (ml/l): 4.467 - 8.078
Phosphate (umol/l): 0.036 - 1.743
Silicate (umol/l): 0.464 - 37.572
Temperature range (°C): -0.849 - 29.546
Nitrate (umol/L): 0.008 - 26.054
Salinity (PPS): 30.381 - 37.431
Oxygen (ml/l): 4.467 - 8.078
Phosphate (umol/l): 0.036 - 1.743
Silicate (umol/l): 0.464 - 37.572
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.
Habitat Type: Marine
Comments: Pelagic, prefers deep water, sometimes around islands or in shallow shelf waters (e.g., 40-70 m; Scott and Sadove 1997). Tend to occur in highest densities near productive waters, and often near steep drop-offs or strong oceanographic features, e.g. edges of continental shelves, large islands, and offshore banks and over submarine trenches and canyons (Gosho et al. 1984, Reeves and Whitehead 1997, Gregr and Trites 2001, Whitehead 2003). Females generally restricted to waters with surface temperatures warmer than about 15 degrees C and rarely found in waters less than 1000 m deep. Males, although primarily found in deep water, are sometimes found in waters 200 to 1000 m deep (Reeves and Whitehead 1997).
- IUCN Red Book, NMFS/NOAA Technical Memo
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.
Seasonal north-south migration; at higher latitudes in summer than in winter. Males move north in the summer to feed. In fall, both sexes migrate toward the equator. In winter, typically distributed south of 40 degrees N. Females, calves, and young remain in tropical or temperate waters while older males migrate to higher latitudes in summer. Males sometimes occur as far north as the Bering Sea.
Physeter catodon feeds mainly on squid (especially giant squid), octopus and deepwater fishes, but it also take sharks and skates. It consumes approximately 3 per cent of its body weight in squid per day.
Animal Foods: fish; mollusks
Primary Diet: carnivore (Molluscivore )
Comments: Eats primarily medium to large squids, sometimes also octopus and various fishes. Large males at high latitudes also take large quantities of demersal and mesopelagic sharks, skates and fishes (Gosho et al. 1984, Jefferson et al.1993, Perry et al. 1999, Whitehead 2003). Dives deeply when foraging, some dives over 1800 m have been recorded, but most are less than 500 m (Potter and Birchler, in Wilson and Ruff 1999). Apparently feeds throughout the year. Although species population depleted by whaling, may take about 75 million metric tons of food from the ocean each year; an amount similar to that taken by all human marine fisheries (Whitehead 2003).
- IUCN Red Book, NMFS/NOAA Technical Memo
Animal / carrion / dead animal feeder
fruitbody of Psilocybe inquilinus feeds on dead washed up bone of Physeter catodon
Other: unusual host/prey
Based on studies in:
This list may not be complete but is based on published studies.
- N. A. Mackintosh, A survey of antarctic biology up to 1945. In: Biologie antarctique, R. Carrick, M. Holdgate, J. Prevost, Eds. (Hermann, Paris, 1964), pp. 3-38.
Known prey organisms
Based on studies in:
This list may not be complete but is based on published studies.
- N. A. Mackintosh, A survey of antarctic biology up to 1945. In: Biologie antarctique, R. Carrick, M. Holdgate, J. Prevost, Eds. (Hermann, Paris, 1964), pp. 3-38.
10,000 to >1,000,000 individuals
Comments: World population in the mid-1980s was estimated at 982,200 (410,700 in the southern ocean, 100,000 in Atlantic, 275,000 in eastern Pacific, 198,000 in western Pacific. Other estimates range from 700,000 to 2 million (Matthews and Moseley 1990). More recently, Whitehead (2003) estimated global population of very approximately 360,000 whales based on extrapolation from visual surveys. None of these estimates should be regarded as particularly precise (see IUCN 1991).
Basic social unit is mixed school of adult females plus their calves and juveniles (usually about 20-40 individuals). As males grow older they leave this group and form bachelor schools (of variable sizes up to about 50 individuals). The largest males tend to be solitary (but see Christal and Whitehead 1997). Likely the world's deepest diving mammal (documented at 2,500 m.).
Life History and Behavior
The major prey of sperm whales is cephalopods (octopuses, squid), though other invertebrates and fish have been found in stomach contents. Primary prey species include squids of the genera Architeuthis (giant squid), Moroteuthis, Gonatopsis, Histioteuthis and Galiteuthis (Jefferson et al, 2008). Sperm whales are exceptionally deep and long divers. Dives of over 2000 metres lasting more than one hour have been recorded, though stomach contents recovered from one individual taken at 3193 metres contained the remains of a bottom-dwelling shark, suggesting deeper dives may be possible (Watkins et al, 1993).
Comments: Active day/night.
Status: wild: 77.0 years.
Lifespan, longevity, and ageing
These whales have a polygamous mating system. During the breeding season, breeding schools composed of 1-5 large males and a mixed group of females and males of various ages form. At this point, there is intense competition among the males for females (including physical competition resulting in battle scars all over the heads of males). Only about 10-25% of fully adult males in a population are able to breed.
Mating System: polygynous
Females mature sexually at 8-11 years, and males mature at approximately 10 years, although males do not mate until 25-27 years old because they do not have a high enough social status in a breeding school until that point. Maximum known life span is 77 years. Gestation period is 14-16 months and a single calf is born, which nurses for up to 2 years. The reproductive cycle occurs in females every 2-5 years. The peak of the mating season is in the spring in both Northern and Southern hemispheres so that most calves are born in the fall.
Breeding interval: The reproductive cycle occurs in females every 2-5 years
Breeding season: The peak of the mating season is in the spring in both Northern and Southern hemispheres
Average number of offspring: 1.
Range gestation period: 14 to 16 months.
Range weaning age: 24 (high) months.
Average weaning age: 24 months.
Range age at sexual or reproductive maturity (female): 8 to 11 years.
Average age at sexual or reproductive maturity (male): 10 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous
Average birth mass: 1e+06 g.
Average number of offspring: 1.
Average age at sexual or reproductive maturity (male)
Sex: male: 3650 days.
Gestation lasts 14-15 months. Births occur May-September in Northern Hemisphere, November-March in Southern Hemisphere. Single young is produced every 3-6 years. Young are weaned in about 1.5-3.5 years, though young may continue to nurse for several years. Females sexually mature at 7-11 years; pregnancy rate gradually declines after age 14. Males may not breed until about 25 years old. May up to at least 60-70 years.
- IUCN Red Book, NMFS/NOAA Technical Memo
Molecular Biology and Genetics
Statistics of barcoding coverage: Physeter macrocephalus
Public Records: 0
Specimens with Barcodes: 1
Species With Barcodes: 1
Barcode data: Physeter catodon
There are 2 barcode sequences available from BOLD and GenBank. Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species. See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Physeter catodon
Public Records: 2
Specimens with Barcodes: 2
Species With Barcodes: 1
Date Listed: 06/02/1970
Lead Region: National Marine Fisheries Service (Region 11)
Where Listed: Entire
Population location: Entire
Listing status: E
For most current information and documents related to the conservation status and management of Physeter macrocephalus, see its USFWS Species Profile
IUCN Red List Assessment
Red List Category
Red List Criteria
- 1994Insufficiently Known(Groombridge 1994)
Sperm whales were once quite abundant in the Gulf of Mexico, but due to commercial whaling operations, they are seldom seen in this area anymore. Worldwide however, sperm whales populations are more stable than that of many other whales, although they continue to be listed as endangered by USDI (1980). The sperm whale is now the most abundant of the great whales, having been hunted with less intensity that the baleen whales. Worldwide, sperm whales number about 1,500,000.
IUCN Red List of Threatened Species: vulnerable
Status in Egypt
National NatureServe Conservation Status
Rounded National Status Rank: N3 - Vulnerable
Rounded National Status Rank: NU - Unrankable
NatureServe Conservation Status
Rounded Global Status Rank: G3 - Vulnerable
Reasons: Occurs widely in all oceans; protected by international and national regulations; total population is large (several hundred thousand) but trend is difficult to determine; threatened by general deterioration of marine ecosystem.
The IUCN Red List (2009) has the sperm whale listed as VU (vulnerable). The species is also currently listed as CITES Appendix I.
Commercial whaling activities were formerly the biggest threat to this species. Entanglement in fishing gear and collision with shipping are also considered potential threats, as are anthropogenic noise disturbance and chemical pollution.
- IUCN Red Book, NMFS/NOAA Technical Memo
The species has a huge geographic range (Rice 1989) and a global population size in the 100,000's (Whitehead 2002; Fig 1). Although there is considerable uncertainty about sperm whale population parameters and levels of exploitation, Whitehead (2002) estimated historical trajectories of sperm whale abundance incorporating many, but not all, sources of uncertainty (Fig. 1 in linked PDF document). That model was modified slightly (to produce an endpoint in 2003) and run to estimate the decline in global sperm whale population size between 1921 and 2003 (i.e. over approximately 3 generations; 82yr; see below for estimation of generation time) (H. Whitehead pers. comm.). As sperm whale population size seems to have changed rather little between about 1910-1930 (Whitehead 2002; Fig. 1 in linked PDF document), the calculations are probably quite robust with reference to the estimated generation time. Using the “best” estimates of the model parameters (as in Whitehead 2002), the population in 2003 would have been 44% of that in 1921. Of 1,000 runs using model parameters randomly selected from within reasonable ranges (as in Whitehead 2002), 6% gave populations in 2003 of <30% of that in 1922, 54% gave a 2003 population between 30-50% of that in 1992, and 40% suggested depletion levels of less than 50% over this time.
Arguments can be made that the model results are overly optimistic or overly pessimistic. Factors that would contribute to making the results overly optimistic that are not accounted for in the model include not accounting for under-reporting of illegal Soviet catches in the North Pacific and Antarctica and under-reporting of Japanese catches in the North Pacific (Kasuya and Brownell 2001), other continuing threats (described below), and factors such as continuing effects of social disruption from whaling that might inhibit recovery (consistent with an apparent lack of recovery in many areas). Factors that would contribute to making the results overly pessimistic include the assumption of a relatively low rate of increase in the model and the extrapolation of a relatively high estimate of g(0) (the proportion of whales detected on the trackline) from a single study to the global population. The direction of the effect of other uncertainties in model inputs, including the effects of sex-biased catches, is not certain. Despite these uncertainties, the Whitehead model provides the best available scientific evidence upon which to base this assessment. To reduce these uncertainties, future analyses would need to address the concerns identified above.
Efforts to assess the conservation status of sperm whales and the impact of historical whaling on contemporary structure are compromised by the absence of a good model of sperm whale population structure; pooling data may obscure distinct geographic patterns. While sperm whales are known to show long distance movements (Ivashin and Rovnin 1967; Mitchell 1975) and low genetic differentiation among ocean basins, several lines of evidence suggest that sperm whales past and present, have significant geographic structure. Analyses based on historical and contemporary data from tagging records (Rice 1974; Kasuya and Miyashita 1988), blood types (Fujino 1963), catch distributions, sighting patterns, size composition, lack of recovery from exploitation (Japan), timing of pregnancy (Best et al.1984), photo-identification (Whitehead 2003), genetics (Drouot 2004; Mesnick et al. 1999), cultural markers (Rendell and Whitehead 2003) and combinations thereof (Bannister and Mitchell 1980; Kasuya and Miyashita 1988) suggest evidence for structure in many regions. Over the past decade, several authors have investigated population structure in female sperm whales using sequence variation within the mitochondrial control region DNA (mtDNA) and/or polymorphic nuclear loci (microsatellites). In general, results tend to find low genetic differentiation among ocean basins and little evidence of subdivision within ocean basins, with the exception of some isolated basins such as the Mediterranean and Gulf of Mexico (Lyrholm et al. 1999; Mesnick et al. 1999; Drouot et al. 2004). However, factors such as low sample sizes, low mtDNA haplotypic diversity and social structure alone and together reduce the power to detect population structure. In addition, it is clear that biologically discrete populations of odontocetes can occur independently of strong geographic or oceanographic features. Alternative, non-geographic based hypotheses of population structure, such as dialect and differences in diet such as are found in killer whales, have not been thoroughly examined. For example, Rendell and Whitehead (2003) suggest that female populations seem to be culturally structured within oceans by “coda” vocalizations and may be genetically distinct (Rendell and Whitehead 2005, Rendell et al. 2005).
Global Short Term Trend: Unknown
Sperm whales have had a long history of local whaling going back at least to the 1500s and intense commercial whaling beginning around 1712 and continuing to 1988. The “modern” highly mechanised phase was particularly intense around 1950, and at its peak killed around 25,000 whales per year, dramatically depleting the global population. In recent decades, some tens of whales were taken each year from small boats in Indonesia (Reeves 2002), although none have been taken in the last two years (H. Whitehead pers. comm.), and 10 are taken annually by Japan under IWC Special Permit (Clapham et al. 2003).
Entanglement in fishing gear, particularly gillnets, has been a particular problem in the Mediterranean Sea (Reeves and Notarbartolo di Sciara, 2006), but sperm whales die from entanglement in nets and lines in many other areas and in a variety of fisheries as well (e.g., Haase and Félix 1994; Barlow and Cameron 2003). Considering the widespread distribution of sperm whales, observations of occasional takes in relatively small scale gillnet fisheries (e.g. Barlow and Cameron 2003) suggest much larger takes in unobserved, unregulated high seas driftnet fisheries such as were common before the 1989 adoption of resolution 44/225 of the UN General Assembly.
Sperm whales sometimes take fish off fishing gear (most often demersal long-line gear), an activity known as “depredation.” Depredation of long-line catches appears to be a recent and increasing phenomenon, and now occurs in many regions (e.g., South East Alaska, Chile, South Georgia and several other southern ocean island areas, North Atlantic). This interaction has resulted in a few reported entanglements and deaths (e.g. Salas 1987; Hucke-Gaete et al. 2004), and has incurred hostility from some fishermen (National Marine Fisheries Service 1998; Donoghue et al. 2003), including shooting of whales (González and Olivarría 2002).
Sperm whale tissues have high levels of some contaminants (O'Shea 1999; Nielsen et al. 2000); however, any population-level effects on health are unknown. The effects of noise on sperm whales are also uncertain. Some evidence suggests that they are highly sensitive to noise (e.g., Watkins et al. 1985; Bowles et al. 1994) while other studies have found little or no effect (e.g., Madsen and Møhl 2000; Madsen et al. 2002). To date, all published studies of sperm whales and noise focus on short-term behavioural effects. Avoidance of sonar (Dawson pers. comm.) and seismic surveys (Mate et al. 1994; but see Madsen et al. 2002) has been observed but no mortality has been documented.
Whaling on sperm whales has at various times focussed almost exclusively on one sex or the other. Removals of large numbers of males may have had lingering effects on pregnancy rates in some subpopulations (Best 1979; Clarke et al. 1980; Whitehead et al. 1997) and large males are noticeably uncommon on some breeding grounds (Whitehead 2003). The removal of large numbers of females from social groups, and of older females in particular, may have lingering, socially disruptive effects. Furthermore, recovery might be inhibited via temporary or permanent loss of social cohesion and of socio-ecological knowledge such as is known to occur in other large-brained, long-lived social mammals (e.g., elephants, Poole and Thomsen 1989).
Maximum rates of increase for sperm whale populations are very low, possibly on the order of 1% per year (Whitehead 2002). Population growth/recovery can be expected to be low in the species.
Sperm whales face other threats at a more regional level. These include collisions with ships (Laist et al. 2001), for instance off the Canary Islands (André and Potter 2000) and in the Mediterranean (Pesante et al. 2002), and ingestion of marine debris in the Mediterranean (e.g., Viale et al. 1992).
Causes for optimism: On the one hand, the sperm whale is not being heavily whaled at present and seems relatively secure from this threat in the short and medium term. When not being actively hunted, the sperm whale has rather little interaction with humans: most of its habitat is far from land, and few of its food sources (principally deep-water squid) are of currently harvested (Clarke 1977). Some populations, for instance the animals in the western North Atlantic that were little affected by modern whaling, seem healthy with reasonably high population densities and evidence of satisfactory reproduction (Gordon et al. 1998; National Marine Fisheries Service 2000).
Causes for concern: on the other hand, the sperm whale, with a maximum rate of increase of around 1% per year (Whitehead 2002), is not well adapted to recover from population depletion. Furthermore, the population model considers only one anthropogenic threat, whaling, and thus posits that the sperm whale population has recovered since about 1980 (Fig. 1 in linked PDF document), when large-scale commercial whaling was rapidly coming to an end. This recovery is purely theoretical, and may not be occurring as sperm whales carry high levels of some chemical contaminants (O'Shea 1999; Nielsen et al. 2000), ocean noise is increasing (Gordon and Moscrop 1996), interactions with fisheries continue to result in sperm whale deaths (International Whaling Commission 1994), and the lingering, socially disruptive effects of whaling may be inhibiting recovery of this highly social species (Whitehead et al. 1997). Some regional populations of sperm whales are declining or are apparently not recovering from depletion. Even in the absence of whaling, the Mediterranean population appears to have declined over the past 20 years, with bycatch in driftnets a likely principal cause (Reeves and Notarbartolo di Sciara 2006). The southeastern Pacific sperm whale population, very heavily whaled during the period 1950-1980, has an extremely low recruitment rate (probably below replacement), perhaps because of the social disruption caused by intense whaling (Whitehead et al. 1997). The population of mature and maturing males in the Antarctic was also heavily whaled over the same period, but should have repopulated from less heavily exploited breeding populations at lower latitudes following the end of large-scale commercial whaling. However, systematic surveys of sperm whales in the Antarctic showed no substantial or statistically significant increase between 1978 and 1992 (Branch and Butterworth 2001).
Degree of Threat: B : Moderately threatened throughout its range, communities provide natural resources that when exploited alter the composition and structure of the community over the long-term, but are apparently recoverable
Comments: Historically hunted for spermaceti, ambergris, and oil. No longer threatened by direct catching, but entanglement in fishing gear may cause mortality in some areas. Potentially threatened by ocean pollution and ingestion of plastics. Since the introduction of fast ferries into the Canary Islands in 1999, significant increases in collisions fatal to whales, mainly sperm whales, have been observed (Tregenza et al. 2004).
Management plans need both development and implementation. The International Whaling Commission manages sperm whale populations under the International Convention for the Regulation of Whaling, and Schedule of the Convention lists sperm whale seasons, sperm whale size limits and sperm whale catch limits (0 at present), as well as sanctuaries for all species in the Indian and Southern Oceans. However, no scheme for managing sperm whale populations is in place. Moreover, many range states are not members of the International Whaling Commission.
Regional subpopulations of sperm whales exist, and there has been an apparent lack of recovery in some areas or even continued decline (e.g., the Mediterranean (Reeves and Notarbartolo di Sciara 2006). Therefore, further assessments of the status of sperm whales should be conducted at the subpopulation level.
Biological Research Needs: Studies needed that combine immunology, toxicology and demography and that involve populations occurring over a gradient of environments, to assess the effects of chemical pollution (Reeves and Reijnders 2002).
Needs: Enforce international and national protection measures. Prevent habitat degradation caused by dumping of toxic wastes, sewage, and garbage.
Relevance to Humans and Ecosystems
Economic Importance for Humans: Negative
Being fiercly aggressive, bull giant sperm whales posed a threat to small-boat whalers in the 19th century. Sperm whales are no match for modern whaling equipment, however. They have also been known to become entangled in trans-Atlantic telephone in dives 3/4 mile deep, but this type of incident is rare.
Economic Importance for Humans: Positive
The head of the sperm whale contains 3-4 tons of spermaceti, a substance valued as a lubricant for fine machinery and a component of automatic transmission fluid. It is also used in making ointments and fine, smokeless candles (once it solidifies into a white wax upon exposure to air). Physeter catodon has also been a target of commercial whaling in years gone by, notably in areas around the Gulf of Mexico. The meat of the whale is not generally consumed. Instead, spermaceti is extracted from the head, and the teeth are often used as a medium for the artistic form of engraving and carving known as scrimshaw. The most important product obtained from giant sperm whales is the oil once used as fuel for lamps and now used as a lubricant and as the base for skin creams and cosmetics. A gummy substance called ambergris forms in the large intestines of sperm whales and can be found floating on the surface of the water or washed ashore once it is expelled. It was once believed to have medicinal qualities, but it is now used in connection with manufacture of perfumes, based on the fact that when it is exposed to air, it hardens and acquires a sweet, earthy smell. The island Ambergris Cay, just south of the Gulf of Mexico, was given its name because of the great quantities of this substance gathered along its shores.
Comments: Source of ambergris (formed in digestive system), which has been used as fixative in perfume industry. Formerly (prior to ban on whaling) a very important commercial species (source of oil, spermaceti, and meal), with annual harvests peaking in the 1960s at 29,000. See IUCN (1991) for information on historical exploitation.
IUCN Red List Category
- IUCN (2008) Cetacean update of the 2008 IUCN Red List of Threatened Species. http://www.marinespecies.org/aphia.php?p=sourcedetails&id=125373
The sperm whale (Physeter macrocephalus), or cachalot, is the largest of the toothed whales. It is the only living member of genus Physeter, and one of three extant species in the sperm whale family, along with the pygmy sperm whale and dwarf sperm whale of the genus Kogia.
Mature males average at 16 metres (52 ft) in length but some may reach 20.5 metres (67 ft), with the head representing up to one-third of the animal's length. The sperm whale feeds primarily on squid. Plunging to 3 kilometres (9,800 ft) for prey, it is the deepest diving mammal. Its clicking vocalization, a form of echolocation and communication, may be as loud as 230 decibels (re 1 µPa at 1 m) underwater, making it the loudest sound produced by any animal. It has the largest brain of any animal on Earth, more than five times heavier than a human's. Sperm whales can live for more than 60 years.
The sperm whale can be found anywhere in the open ocean. Females and young males live together in groups while mature males live solitary lives outside of the mating season. The females cooperate to protect and nurse their young. Females give birth every four to twenty years, and care for the calves for more than a decade. A mature sperm whale has few natural predators. Calves and weakened adults are taken by pods of orcas.
From the early eighteenth century through the late 20th the species was a prime target of whalers. The head of the whale contains a liquid wax called spermaceti, from which the whale derives its name. Spermaceti was used in lubricants, oil lamps, and candles. Ambergris, a waste product from its digestive system, is still used as a fixative in perfumes. Occasionally the sperm whale's great size allowed it to defend itself effectively against whalers. The species is now protected by a whaling moratorium, and is currently listed as vulnerable by the IUCN.
- 1 Etymology
- 2 Description
- 3 Vocalization complex
- 4 Ecology
- 5 Life cycle
- 6 Social behaviour
- 7 Diet
- 8 Sleeping
- 9 Taxonomy and naming
- 10 Evolutionary history
- 11 Relationship with humans
- 12 See also
- 13 Notes
- 14 References
- 15 Further reading
- 16 External links
The name sperm whale is an apocopation of spermaceti whale. Spermaceti, originally mistakenly identified as the whales' semen, is the semi-liquid, waxy substance found within the whale's head (see below). The sperm whale is also known as the "cachalot", which is thought to derive from the archaic French for "tooth" or "big teeth", as preserved for example in cachau in the Gascon dialect (a word of either Romance or Basque origin). The etymological dictionary of Corominas says the origin is uncertain, but it suggests that it comes from the Vulgar Latin cappula, plural of cappulum, sword hilt. According to Encarta Dictionary, the word cachalot came to English "via French from Spanish or Portuguese cachalote, perhaps from Galecian/Portuguese cachola, 'big head'". The term is retained in the Russian word for the animal, кашалот (kashalot), as well as in many other languages.
|Male||16 metres (52 ft)||41,000 kilograms (45 short tons)|
|Female||11 metres (36 ft)||14,000 kilograms (15 short tons)|
|Newborn||4 metres (13 ft)||1,000 kilograms (1.1 short tons)|
The sperm whale is the largest toothed whale, with adult males measuring up to 20.5 metres (67 ft) long and weighing up to 57,000 kilograms (56 long tons; 63 short tons). By contrast, the second largest toothed whale, Baird's Beaked Whale measures 12.8 metres (42 ft) and weighs up to 15 short tons (14,000 kg). The Nantucket Whaling Museum has a 5.5 metres (18 ft)-long jawbone. The museum claims that this individual was 80 feet (24 m) long; the whale that sank the Essex (one of the incidents behind Moby-Dick) was claimed to be 85 feet (26 m). A similar size is reported from a jawbone from the British Natural History Museum. A 67-foot specimen also is reported from a Soviet whaling fleet near the Kurile Islands in summer of 1950. However, there is disagreement on the claims of adult males approaching or exceeding 80 feet (24 m) in length.
Extensive whaling may have decreased their size, as males were highly sought, primarily after World War II. Today, males do not usually exceed 18.3 metres (60 ft) in length or 51,000 kilograms (50 long tons; 56 short tons) in weight. Another view holds that exploitation by overwhaling had virtually no effect on the size of the bull sperm whales, and their size may have actually increased in current times on the basis of density dependent effects.
The sperm whale's unique body is unlikely to be confused with any other species. The sperm whale's distinctive shape comes from its very large, block-shaped head, which can be one-quarter to one-third of the animal's length. The S-shaped blowhole is located very close to the front of the head and shifted to the whale's left. This gives rise to a distinctive bushy, forward-angled spray.
The sperm whale's flukes are triangular and very thick. Proportionally, they are larger than that of any other cetacean, and are very flexible. The whale lifts its flukes high out of the water as it begins a feeding dive. It has a series of ridges on the back's caudal third instead of a dorsal fin. The largest ridge was called the 'hump' by whalers, and can be mistaken for a dorsal fin because of its shape and size.
|Sperm whale skeleton|
The ribs are bound to the spine by flexible cartilage, which allows the ribcage to collapse rather than snap under high pressure.
As with other toothed whales, the skull of the sperm whale is asymmetrical so as to aid echolocation. Sound waves that strike the whale from different directions will not be channeled in the same way. Within the basin of the cranium, the openings of the bony narial tubes (from which the nasal passages spring) are skewed towards the left side of the skull.
Jaws and teeth
The sperm whale's lower jaw is very narrow and underslung. The sperm whale has 18 to 26 teeth on each side of its lower jaw which fit into sockets in the upper jaw. The teeth are cone-shaped and weigh up to 1 kilogram (2.2 lb) each. The teeth are functional, but do not appear to be necessary for capturing or eating squid, as well-fed animals have been found without teeth or even deformed jaws. One hypothesis is that the teeth are used in aggression between males. Mature males often show scars which seem to be caused by the teeth. Rudimentary teeth are also present in the upper jaw, but these rarely emerge into the mouth. Analyzing the teeth is the preferred method for determining a whale's age; analogous to rings in a tree, the teeth build distinct layers of cementum and dentine as they grow.
Respiration and diving
Sperm whales, along with bottlenose whales and elephant seals, are the deepest-diving mammals. Sperm whales are believed to be able to reach 3 kilometres (1.9 mi) in depth and remain submerged for 90 minutes. More typical dives are around 400 metres (1,300 ft) and 35 minutes in duration. At these great depths, sperm whales had sometimes become entangled in transoceanic telephone cables and drowned until improvements in laying and maintenance techniques were employed.
The sperm whale has adapted to cope with drastic pressure changes when diving. The flexible ribcage allows lung collapse, reducing nitrogen intake, and metabolism can decrease to conserve oxygen. Myoglobin, which stores oxygen in muscle tissue, is much more abundant than in terrestrial animals. The blood has a high red blood cell density, which contain oxygen-carrying haemoglobin. The oxygenated blood can be directed towards only the brain and other essential organs when oxygen levels deplete. The spermaceti organ may also play a role by adjusting buoyancy (see below).
While sperm whales are well adapted to diving, repeated dives to great depths have long term effects. Bones show the same pitting that signals decompression sickness in humans. Older skeletons showed the most extensive pitting, whereas calves showed no damage. This damage may indicate that sperm whales are susceptible to decompression sickness, and sudden surfacing could be lethal to them.
Between dives, the sperm whale surfaces to breathe for about eight minutes before diving again. Odontoceti (toothed whales) breathe air at the surface through a single, S-shaped blowhole. Sperm whales spout (breathe) 3–5 times per minute at rest, increasing to 6–7 times per minute after a dive. The blow is a noisy, single stream that rises up to 2 metres (6.6 ft) or more above the surface and points forward and left at a 45° angle. On average, females and juveniles blow every 12.5 seconds before dives, while large males blow every 17.5 seconds before dives.
Brain and senses
The brain is the largest known of any modern or extinct animal, weighing on average about 7.8 kilograms (17 lb), more than five times heavier than a human's, and has a volume of about 8,000 cm3. Although larger brains generally correlate with higher intelligence, it is not the only factor. Elephants and dolphins also have larger brains than humans. The sperm whale has a lower encephalization quotient than many other whale and dolphin species, lower than that of non-human anthropoid apes, and much lower than humans'.
The sperm whale's cerebrum is the largest in all mammalia, both in absolute and relative terms. The olfactory system is reduced, suggesting that the sperm whale has a poor sense of taste and smell. By contrast, the auditory system is enlarged. The pyramidal tract is poorly developed, reflecting the reduction of its limbs.
The sperm whale has two stomachs. The first secretes no gastric juices, and instead crushes the food with its strong muscular walls (whales can't chew). Digestion proper takes place in the second stomach.
The heart's mass accounts for 2.5% of the whale's body weight.
The sperm whale's eye does not differ greatly from those of other toothed whales except in size. It is the largest among the toothed whales, weighing about 170g. It is overall ellipsoid in shape, compressed along the visual axis, measuring about 7x7x3 cm. The cornea is elliptical and the lens is spherical. The sclera is very hard and thick, roughly 1 cm anteriorly and 3 cm posteriorly. There are no ciliary muscles. The choroid is very thick and contains a fibrous tapetum lucidum. Like other toothed whales, the sperm whale can retract and protrude its eyes thanks to a 2-cm-thick retractor muscle attached around the eye at the equator.
Spermaceti organ and melon
Atop the whale's skull is positioned a large complex of organs filled with a liquid mixture of fats and waxes called spermaceti. The purpose of this complex is to generate powerful and focused clicking sounds, which the sperm whale uses for echolocation and communication.
The spermaceti organ is like a large barrel of spermaceti. Its surrounding wall, known as the case, is extremely tough and fibrous. The case can hold within it up to 1,900 litres of spermaceti. It is proportionately larger in males. This oil is a mixture of triglycerides and wax esters. The proportion of wax esters in the spermaceti organ increases with the age of the whale: 38–51% in calves, 58–87% in adult females, and 71–94% in adult males. The spermaceti at the core of the organ has a higher wax content than the outer areas. The speed of sound in spermaceti is 2,684 m/s (at 40 kHz, 36°C), making it nearly twice as good a conductor of sounds as the oil in a dolphin's melon. Below the spermaceti organ lies the "junk" (so-called because many whalers dismissed this part as a worthwhile source of oil), which consists of compartments of spermaceti separated by cartilage. It is analogous to the melon found in other toothed whales.
Running through the head are two air passages. The left passage runs alongside the spermaceti organ and goes directly to the blowhole, whilst the right passage runs underneath the spermaceti organ and passes air through a pair of phonic lips and into the distal sac at the very front of the nose. The distal sac is connected to the blowhole and the terminus of the left passage. When the whale is submerged, it can close the blowhole, and air that passes through the phonic lips can circulate back to the lungs.
At the posterior end of this spermaceti complex is the frontal sac, which covers the concave surface of the cranium. The posterior wall of the frontal sac is covered with fluid–filled knobs, which are about 4–13mm in diameter and separated by narrow grooves. The anterior wall is smooth. The knobbly surface reflects sound waves that come through the spermaceti organ from the phonic lips. The grooves between the knobs trap a film of air that is consistent whatever the orientation or depth of the whale, making it an excellent sound mirror.
The spermaceti organs may also help adjust the whale's buoyancy. It is hypothesized that before the whale dives, cold water enters the organ, and it is likely that the blood vessels constrict, reducing blood flow, and, hence, temperature. The wax therefore solidifies and reduces in volume. The increase in specific density generates a down force of about 392 newtons (88 lbf) and allows the whale to dive with less effort. During the hunt, oxygen consumption, together with blood vessel dilation, produces heat and melts the spermaceti, increasing its buoyancy and enabling easy surfacing. However, more recent work have found many problems with this theory including the lack of anatomical structures for the actual heat exchange.
Herman Melville's fictional story Moby Dick suggests that the "case" containing the spermaceti serves as a battering ram for use in fights between males. Apart from a few famous instances such as the well-documented sinking of the ships Essex and Ann Alexander by attackers estimated to weigh only one-fifth as much as the ships, this hypothesis is not well supported in current scientific literature.
A piece of the posterior wall of the frontal sac. The grooves between the knobs trap a consistent film of air, making it an excellent sound mirror.
Differences from other toothed whales
The sperm whale's head anatomy is very unusual among odontocetes. The sperm whale has only one pair of phonic lips, whereas all other toothed whales have two, and it is located at the front of the nose instead of behind the melon.
When echolocating, the sperm whale emits a directionally focused beam of broadband clicks. Clicks are generated by the forcing of air through a pair of phonic lips (also known as "monkey lips" or "museau de singe") at the front end of the nose, just below the blowhole. The sound then travels backwards along the length of the nose through the spermaceti organ. Most of the sound energy is then reflected off the frontal sac at the cranium and into the junk, whose lens-like structure focuses it. Some of the sound will reflect back into the spermaceti organ and back towards the front of the whale's nose where it will be reflected through the spermaceti organ a third time. This back and forth reflection which happens on the scale of a few milliseconds creates a multi-pulse click structure. This multi-pulse click structure actually allows researchers to measure the whale's spermaceti organ using only the sound of its clicks, and given the size of the spermaceti organ in relation to the size of the whale, biologists can measure the whales by recording their echolocation clicks. Because the IPI of a Sperm Whale's click is related to the length of the sound producing organ, an individual whale's click is unique to that individual. However, if the whale matures and the size of the spermaceti organ increases, the tone of the whale's click will also change. The lower jaw is the primary reception path for the echoes. A continuous fat-filled canal transmits received sounds to the inner ear.
The source of the air forced through the phonic lips is the right nasal passage. While the left nasal passage opens to the blow hole, the right nasal passage has evolved to supply air to the phonic lips. It is thought that the nostrils of the land-based ancestor of the sperm whale migrated through evolution to their current functions, the left nostril becoming the blowhole and the right nostril becoming the phonic lips.
Air that passes through the phonic lips passes into the distal sac, then back down through the left nasal passage. This recycling of air allows the whale to continuously generate clicks for as long as it is submerged.
Types of vocalization
A creak is a rapid series of high-frequency clicks that sounds somewhat like a creaky door hinge. It is typically used when homing in on prey.
A coda is a short pattern of 3 to 20 clicks that is used in social situations. They were once thought to be a way by which individuals identified themselves, but individuals have been observed producing multiple codas, and the same codas are used by multiple individuals. Geographically separate pods exhibit distinct dialects. Large males are generally solitary and rarely produce codas. In breeding grounds, codas are almost entirely produced by adult females. Despite evidence that Sperm whales share similar codas, it is still unknown whether sperm whales possess individually specific coda repertoires or whether individuals make codas at different rates.
Slow clicks are heard only in the presence of males (it is not certain whether females occasionally make them). Males make a lot of slow clicks in breeding grounds (74% of the time), both near the surface and at depth, which suggests they are primarily mating signals. Outside breeding grounds, slow clicks are rarely heard, and usually near the surface.
|Click type||Apparent source level|
(dB re 1µPa [Rms])
|Duration of click|
|Duration of pulse|
|Range audible to sperm whale|
|Inferred function||Audio sample|
|Usual||230||High||15||0.5–1.0||15–30||0.1||16||searching for prey|
|Creak||205||High||15||0.005–0.1||0.1–5||0.1||6||homing in on prey|
|Slow||190||Low||0.5||5–8||30||5||60||communication by males|
The sperm whale is among the most cosmopolitan species. It prefers ice-free waters over 1,000 metres (3,300 ft) deep. Although both sexes range through temperate and tropical oceans and seas, only adult males populate higher latitudes.
It is relatively abundant from the poles to the equator and is found in all the oceans. It inhabits the Mediterranean Sea, but not the Black Sea, while its presence in the Red Sea is uncertain. The shallow entrances to both the Black Sea and the Red Sea may account for their absence. The Black Sea's lower layers are also anoxic and contain high concentrations of sulphur compounds such as hydrogen sulphide.
Populations are denser close to continental shelves and canyons. Sperm whales are usually found in deep off-shore waters, but may be seen closer to shore in areas where the continental shelf is small and drops quickly to depths of 310–920 metres (1,020–3,020 ft). Coastal areas with significant sperm whale populations include the Azores and the Caribbean island of Dominica.
Sperm whales can live 70 years or more. They are a prime example of a species that has been K-selected, i.e., their reproductive strategy is associated with stable environmental conditions and comprises a low birth rate, significant parental aid to offspring, slow maturation, and high longevity.
How they choose mates has not been definitively determined. Males will fight with each other over females, and males will mate with multiple females, but they do not dominate the group like a harem. Males do not provide paternal care to their offspring.
Females become fertile at around 9 years of age. The oldest pregnant female ever recorded was 41 years old. Gestation requires 14 to 16 months, producing a single calf. Sexually mature females give birth once every 4 to 20 years (pregnancy rates were higher during the whaling era). Birth is a social event, as the mother and calf needs others to protect them from predators. The other adults may jostle and bite the newborn in its first hours.
Lactation proceeds for 19 to 42 months, but calves may suckle up to 13 years (although usually less). Like other whales, the sperm whale's milk has a higher fat content than that of terrestrial mammals: about 36%, compared to 4% in cow milk. This gives it a consistency similar to cottage cheese, which prevents it from dissolving in the water before the calf can eat it. It has an energy content of roughly 3,840 kcal/kg (16,070 kJ/kg), compared to just 640 kcal/kg (2,700 kJ/kg) in cow milk. Calves may be allowed to suckle from females other than their mothers.
Males become sexually mature at 18 years. Upon reaching sexual maturity, males move to higher latitudes, where the water is colder and feeding is more productive. Females remain at lower latitudes. Males reach their full size at about age 50.
Adult males who are not breeding live solitary lives, whereas females and juvenile males live together in groups. The main driving force for the sexual segregation of adult sperm whales is scramble competition for mesopelagic squid.
Females and their young remain in groups, while mature males leave their "natal unit" somewhere between 4 and 21 years of age. Mature males sometimes form loose "bachelor groups" with other males of similar age and size. As males grow older, they typically live solitary lives. Mature males have beached themselves together, suggesting a degree of cooperation which is not yet fully understood. The whales rarely if ever leave their group.
A social unit is a group of sperm whales who live and travel together over periods of years. Individuals rarely, if ever, join or leave a social unit. There is a huge variance in the size of social units. They are most commonly between 6 and 9 individuals in size but can have more than twenty. Unlike orcas, sperm whales within a social unit show no significant tendency to associate with their genetic relatives. Females and calves spend about three quarters of their time foraging and a quarter of their time socializing. Socializing usually takes place in the afternoon.
When sperm whales socialize, they emit complex patterns of clicks called codas (see above). They will spend much of the time rubbing against each other.
Relations with other species
The most common non-human attacker of sperm whales is the orca, but pilot whales and the false killer whale also sometimes harass them. Orcas prey on target groups of females with young, usually making an effort to extract and kill a calf. The adults will protect their calves or an injured adult by encircling them. They may face inwards with their tails out; the Marguerite formation (named after the flower). The heavy and powerful tail of an adult whale can deliver lethal blows. Alternatively, they will face outwards; the heads-out formation. Early whalers exploited this behaviour, attracting a whole unit by injuring one of its members. If the orca pod is extremely large, its members may sometimes be able to kill adult female sperm whales. Individual large mature male sperm whales have no non-human predators, and are believed to be too large, powerful and aggressive to be threatened by orcas. In addition, male sperm whales have been observed to attack and intimidate orca pods. A recent incident[when?] was filmed from a long-line trawler; an orca pod was systematically taking fish caught on the trawler's long lines (as the lines were being pulled into the ship) when a male sperm whale appeared to repeatedly charge the orca pod in attempt to drive them away; it was speculated by the film crew that the sperm whale was attempting access the same fish. Ironically the orcas also engaged in a similar tail first and tail slapping defensive position against the bull sperm whale as is used by female sperm whales against attacking orcas.
The sperm whales are not known for forging bonds with other species, but it was observed that a bottlenose dolphin with spinal deformity had been accepted into a pod of sperm whales.
Sperm whales usually dive between 300 to 800 metres (980 to 2,600 ft), and sometimes 1–2 kilometres (3,300–6,600 ft) to search for food. Such dives can last more than an hour. They feed on several species, notably the giant squid, but also the larger colossal squid, octopuses, and diverse fish like demersal rays, but the main part of their diet consists of medium-sized squid. Some prey may be taken incidentally while eating other items. Most of what is known about deep sea squid has been learned from specimens in captured sperm whale stomachs, although more recent studies analysed feces. One study, carried out around the Galápagos, found that squid from the genera Histioteuthis (62%), Ancistrocheirus (16%), and Octopoteuthis (7%) weighing between 12 and 650 grams (0.026 and 1.43 lb) were the most commonly taken. Battles between sperm whales and giant squid or colossal squid have never been observed by humans; however white scars are believed to be caused by the large squid. One study published in 2010 collected evidence that suggests that female sperm whales may collaborate when hunting Humboldt squid. Tagging studies have shown that sperm whales hunt upside down at the bottom of their deep dives. It is suggested that the whales can see the squid silhouetted above them against the dim surface light.
An older study, examining whales captured by the New Zealand whaling fleet in the Cook Strait region, found a 1.69:1 ratio of squid to fish by weight. Sperm whales sometimes steal sablefish and toothfish from long lines. Long-line fishing operations in the Gulf of Alaska complain that sperm whales take advantage of their fishing operations to eat desirable species straight off the line, sparing the whales the need to hunt. However, the amount of fish taken is very little compared to what the sperm whale needs per day. Video footage has been captured of a large male sperm whale "bouncing" a long line, to gain the fish. Sperm whales are believed to prey on the megamouth shark, a rare and large deep-sea species discovered in the 1970s. In one case, three sperm whales were observed attacking or playing with a megamouth.
The sharp beak of a consumed squid lodged in the whale's intestine may lead to the production of ambergris, analogous to the production of pearls. The irritation of the intestines caused by squid beaks stimulates the secretion of this lubricant-like substance. Sperm whales are prodigious feeders and eat around 3% of their body weight per day. The total annual consumption of prey by sperm whales worldwide is estimated to be about 100,000,000 short tons (91,000,000 t) — a figure greater than the total consumption of marine animals by humans each year.
Sperm whales hunt through echolocation. Their clicks are the most powerful sounds in the animal kingdom (see above). It has been hypothesised that it can stun prey with its clicks. Experimental studies attempting to duplicate this effect have been unable to replicate the supposed injuries, casting doubt on this idea.
It has been stated that sperm whales help to fertilise the surface of the ocean by consuming nutrients at depth and transporting those nutrients to the oceans' surface when they defecate. This fertilises the plants (phytoplankton) on the surface of the ocean and contributes to ocean productivity and the drawdown of atmospheric carbon.
For some time researchers have been aware that pods of sperm whales may sleep for short periods, assuming a vertical position with their heads just below or at the surface. A 2008 study published in Current Biology recorded evidence that whales may sleep with both sides of the brain. It appears that some whales may fall into a deep sleep for about 7 percent of the time, most often between 6 p.m. and midnight.
Taxonomy and naming
The sperm whale belongs to the order Cetacea, the order containing all whales and dolphins. It is a member of the suborder Odontoceti, the suborder containing all the toothed whales and dolphins. It is the sole extant species of its genus, Physeter, in the family Physeteridae. Two species of the related extant genus Kogia, the pygmy sperm whale Kogia breviceps and the dwarf sperm whale K. simus, are placed either in this family or in the family Kogiidae. In some taxonomic schemes the families Kogiidae and Physeteridae are combined as the superfamily Physeteroidea (see the separate entry on the sperm whale family).
The sperm whale is one of the species originally described by Linnaeus in 1758 in his eighteenth century work, Systema Naturae. He recognised four species in the genus Physeter. Experts soon realised that just one such species exists, although there has been debate about whether this should be named P. catodon or P. macrocephalus, two of the names used by Linnaeus. Both names are still used, although most recent authors now accept macrocephalus as the valid name, limiting catodon's status to a lesser synonym.[a]
Although the fossil record is poor, several extinct genera have been assigned to the clade Physeteroidea, which includes the last common ancestor of the modern sperm whale, pygmy sperm whale and dwarf sperm whale, plus all of that ancestor's descendants. These fossils include Ferecetotherium, Idiorophus, Diaphorocetus, Aulophyseter, Orycterocetus, Scaldicetus, Placoziphius, Zygophyseter and Acrophyseter. Ferecetotherium, found in Azerbaijan and dated to the late Oligocene (about ), is the most primitive fossil that has been found which possesses sperm whale-specific features such as an asymmetric rostrum ("beak" or "snout"). Most sperm whale fossils date from the Miocene period, . Diaphorocetus, from Argentina, has been dated to the early Miocene. Fossil sperm whales from the Middle Miocene include Aulophyseter, Idiorophus and Orycterocetus, all of which were found on the west coast of the United States, and Scaldicetus, found in Europe and Japan. Orycterocetus fossils have also been found in the North Atlantic Ocean and the Mediterranean Sea, in addition to the west coast of the United States. Placoziphius, found in Europe, and Acrophyseter, from Peru, are dated to the late Miocene.
|Evolutionary family tree of sperm whales,|
including simplified summary of extinct groups (†)
Fossil sperm whales differ from modern sperm whales in tooth count and the shape of the face and jaws. For example Scaldicetus had a tapered rostrum. Genera from the Oligocene and early and middle Miocene, with the possible exception of Aulophyseter, had teeth in their upper jaws. Acrophyseter, from the late Miocene, also had teeth in both the upper and lower jaws as well as a short rostrum and an upward curving mandible (lower jaw). These anatomical differences suggest that fossil species may not have necessarily been deep-sea squid eaters like the modern sperm whale, but that some genera mainly ate fish. Zygophyseter, dated from the middle to late Miocene and found in southern Italy, had teeth in both jaws and appears to have been adapted to feed on large prey, rather like the modern Orca (Killer Whale).
The traditional view has been that Mysticeti (baleen whales) and Odontoceti (toothed whales) arose from more primitive whales early in the Oligocene period, and that the super-family Physeteroidea, which contains the sperm whale, dwarf sperm whale, and pygmy sperm whale, diverged from other toothed whales soon after that, over . In 1993–96 molecular phylogenetics analyses by Milinkovitch and colleagues, based on comparing the genes of various modern whales, suggested that the sperm whales are more closely related to the baleen whales than they are to other toothed whales, which would have meant that Odontoceti were not monophyletic; in other words, it did not consist of a single ancestral toothed whale species and all its descendants. However, more recent studies, based on various combinations of comparative anatomy and molecular phylogenetics, criticised Milinkovitch's analysis on technical grounds and reaffirmed that the Odontoceti are monophyletic.
These analyses also confirm that there was a rapid evolutionary radiation (diversification) of the Physeteroidea in the Miocene period. The Kogiidae (dwarf and pygmy sperm whales) diverged from the Physeteridae (true sperm whales) at least .
Relationship with humans
Spermaceti, obtained primarily from the spermaceti organ, and sperm oil, obtained primarily from the blubber in the body, were much sought after by eighteenth, nineteenth, and twentieth century whalers. These substances found a variety of commercial applications, such as candles, soap, cosmetics, machine oil, other specialized lubricants, lamp oil, pencils, crayons, leather waterproofing, rust-proofing materials and many pharmaceutical compounds. Ambergris, a solid, waxy, flammable substance produced in the digestive system of sperm whales, was also sought as a fixative in perfumery.
Prior to the early eighteenth century, hunting was mostly by indigenous Indonesians. Legend has it that sometime in the early eighteenth century, around 1712, Captain Christopher Hussey, while cruising for right whales near shore, was blown offshore by a northerly wind, where he encountered a sperm whale pod and killed one. Although the story may not be true, sperm whales were indeed soon exploited by American whalers. Judge Paul Dudley, in his Essay upon the Natural History of Whales (1725), states that one Atkins, ten or twelve years in the trade, was among the first to catch sperm whales sometime around 1720 off the New England coast.
There were only a few recorded catches during the first few decades (1709–1730s) of offshore sperm whaling. Instead sloops concentrated on Nantucket Shoals where they would have taken right whales or went to the Davis Strait region to catch bowhead whales. By the early 1740s, with the advent of spermaceti candles (before 1743), American vessels began to focus on sperm whales. The diary of Benjamin Bangs (1721–1769) shows that, along with the bumpkin sloop he sailed, he found three other sloops flensing sperm whales off the coast of North Carolina in late May 1743. On returning to Nantucket in the summer 1744 on a subsequent voyage he noted that "45 spermacetes are brought in here this day," another indication that American sperm whaling was in full swing.
American sperm whaling soon spread from the east coast of the American colonies to the Gulf Stream, the Grand Banks, West Africa (1763), the Azores (1765), and the South Atlantic (1770s). From 1770 to 1775 Massachusetts, New York, Connecticut, and Rhode Island ports produced 45,000 barrels of sperm oil annually, compared to 8,500 of whale oil. In the same decade the British began sperm whaling, employing American ships and personnel. By the following decade the French had entered the trade, also employing American expertise. Sperm whaling increased until the mid-nineteenth century. Spermaceti oil was important in public lighting (for example, in lighthouses, where it was used in the United States until 1862, when it was replaced by lard oil, in turn replaced by petroleum) and for lubricating the machines (such as those used in cotton mills) of the Industrial Revolution. Sperm whaling declined in the second half of the nineteenth century, as petroleum came into broader use. In that sense, it may be said to have protected whale populations from even greater exploitation. Sperm whaling in the eighteenth century began with small sloops carrying only one or two whaleboats. The fleet's scope and size increased over time, and larger ships entered the fishery. In the late eighteenth century and early nighteenth century sperm whaling ships sailed to the equatorial Pacific, the Indian Ocean, Japan, the coast of Arabia, Australia and New Zealand. Hunting could be dangerous to the crew, since sperm whales (especially bulls) will readily fight to defend themselves against attack, unlike most baleen whales. When dealing with a threat, sperm whales will use their huge head effectively as a battering ram. Arguably the most famous sperm whale counterattack occurred on 20 November 1820, when a whale claimed to be about 25.9 metres (85 ft) long rammed and sank the Nantucket whaleship Essex. Only 8 out of 21 sailors survived to be rescued by other ships. This instance is popularly believed to have inspired Herman Melville's famous book "Moby-Dick".
The sperm whale's ivory-like teeth were often sought by 18th and 19th-century whalers, who used them to produce inked carvings known as scrimshaw. Thirty teeth of the sperm whale can be used for ivory. Each of these teeth (up to 8 inches long and 3 inches across), are hollow for the first half of their length. Like walrus ivory, sperm whale ivory has two distinct layers. However, sperm whale ivory contains a much thicker inner layer. Though a widely practiced art in the nineteenth century, scrimshaw using genuine sperm whale ivory declined substantially after the retirement of the whaling fleets in the 1880s. Currently the Endangered Species Act and CITES, the Convention on International Trade in Endangered Species of Wild Fauna and Flora, prevents the sales of or trade in sperm whale ivory harvested after 1973 or in scrimshaw crafted from it.
Modern whaling was more efficient than open-boat whaling, employing steam-powered ships and exploding harpoons. Initially, modern whaling activity focused on large baleen whales, but as these populations were taken, sperm whaling increased. This was especially true during World War II when spermaceti, the fine waxy oil produced by sperm whales, was in high demand for lubricating the American war machine[clarification needed]. In both the 1941-2 and 1942-3 seasons, the Norwegian expedition took over 3,000 sperm whales off the coast of Peru alone. After the war whaling continued unabated to obtain oil for cosmetics and high-performance machinery, such as automobile transmissions.
The hunting led to the near extinction of large whales including sperm whales until bans on whale oil use were instituted in 1972. The International Whaling Commission gave the species full protection in 1985 but hunting by Japan in the northern Pacific Ocean continued until 1988.
It is estimated that the historic worldwide population numbered 1,100,000 before commercial sperm whaling began in the early eighteenth century. By 1880 it had declined by an estimated 29 per cent. From that date until 1946 the population appears to have recovered somewhat as whaling pressure lessened, but after the Second World War, the population declined even further, to only 33 per cent of the pre-whaling era. It has been estimated that in the nineteenth century between 184,000 and 236,000 sperm whales were killed by the various whaling nations, while in the modern era, at least 770,000 were taken, the majority between 1946 and 1980.
Sperm whales increase the levels of primary production and carbon export by depositing iron rich faeces into surface waters of the Southern Ocean. The iron rich faeces cause phytoplankton to grow and take up more carbon from the atmosphere. When the phytoplankton dies, it sinks to the deep ocean and takes the atmospheric carbon with it. By reducing the abundance of sperm whales in the Southern Ocean, whaling has resulted in an extra 2 million tonnes of carbon remaining in the atmosphere each year.
Remaining sperm whale populations are large enough that the species' conservation status is rated as vulnerable rather than endangered. However, the recovery from the whaling years is a slow process, particularly in the South Pacific, where the toll on breeding-age males was severe.
Current conservation status
The number of sperm whales throughout the world is unknown, but is thought to be in the hundreds of thousands. The conservation outlook is brighter than for many other whales. Historically, Japan has taken ten sperm whales a year, and until 2006 tens of these whales were hunted off Indonesia. They are protected practically worldwide, and commercial whaling has ceased. Fishermen do not target the creatures that sperm whales eat. However, long-line fishing operations in the Gulf of Alaska have complained about sperm whales stealing fish from their lines.
Entanglement in fishing nets and collisions with ships represent the greatest threats to the sperm whale population currently. Other current threats include ingestion of marine debris, ocean noise, and chemical pollution. The IUCN regards the sperm whale as being "vulnerable". The species is listed as endangered on the United States Endangered Species Act.
The species is listed on Appendix I and Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). It is listed on Appendix I as this species has been categorized as being in danger of extinction throughout all or a significant proportion of their range and CMS Parties strive towards strictly protecting these animals, conserving or restoring the places where they live, mitigating obstacles to migration and controlling other factors that might endanger them. It is listed on Appendix II as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements. It is also covered by the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS) and Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MOU).
Rope-mounted teeth are important cultural objects throughout the Pacific. In New Zealand, the Māori know them as "rei puta"; such whale tooth pendants were rare objects because sperm whales were not actively hunted in traditional Māori society. Whale ivory and bone were taken from beached whales. In Fiji the teeth are known as tabua and they were traditionally given as gifts for atonement or esteem (called sevusevu), and were important in negotiations between rival chiefs. Friedrich Ratzel in The History of Mankind reported in 1896 that, in Fiji, whales' or cachalots' teeth were the most-demanded article of ornament or value. They occurred often in necklaces. Today the tabua remains an important item in Fijian life. The teeth were originally rare in Fiji and Tonga, which exported teeth, but with the Europeans' arrival, teeth flooded the market and this "currency" collapsed. The oversupply led in turn to the development of the European art of scrimshaw.
Herman Melville's novel Moby-Dick is based on a true story about a sperm whale that attacked and sank the whaleship Essex. Melville associated the sperm whale with the Bible's Leviathan. The fearsome reputation perpetuated by Melville was based on bull whales' ability to fiercely defend themselves from attacks by early whalers, occasionally resulting in the destruction of the whaling ships.
The sperm whale was designated as the Connecticut state animal by the CT General Assembly in 1975. It was selected because of its specific contribution to the state's history and because of its present-day plight as an endangered species.
Watching sperm whales
Sperm whales are not the easiest of whales to watch, due to their long dive times and ability to travel long distances underwater. However, due to the distinctive look and large size of the whale, watching is increasingly popular. Sperm whale watchers often use hydrophones to listen to the clicks of the whales and locate them before they surface. Popular locations for sperm whale watching include the town of Kaikoura on New Zealand's South Island, Andenes and Tromsø in Arctic Norway; as well as the Azores, where the continental shelf is so narrow that whales can be observed from the shore, and Dominica where a long-term scientific research program, The Dominica Sperm Whale Project, has been in operation since 2005.
- a Until 1974 the species was generally known as P. catodon. In that year, however, Husson & Holthuis proposed that the correct name should be P. macrocephalus, the second name in the genus Physeter published by Linnaeus concurrently with P. catodon. This proposition was based on the grounds that the names were synonyms published simultaneously, and, therefore, the ICZN Principle of the First Reviser should apply. In this instance, it led to the choice of P. macrocephalus over P. catodon, a view re-stated in Holthuis, 1987. This has been adopted by most subsequent authors, although Schevill (1986 and 1987) argued that macrocephalus was published with an inaccurate description and that therefore only the species catodon was valid, rendering the principle of "First Reviser" inapplicable. At the present time, the name P. catodon is used in the Catalogue of Life. However, this is expected to be changed to follow the most recent version of ITIS, which has recently altered its usage from P. catodon to P. macrocephalus following L. B. Holthuis, and more recent (2008) discussions with relevant experts (refer cited ITIS page for additional information).
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Names and Taxonomy
Comments: There is disagreement over the correct specific name. Linnaeus used both macrocephalus and catodon in the 10th edition of Systema Naturae. Leatherwood and Reeves (1983) and many other authors have used the name P. macrocephalus. Recently, Schevill (1986) argued that catodon is the correct name, whereas Holthius (1987) responded that macrocephalus is correct. Jones et al. (1986) stated that the change to catodon was unjustified because it was based on a misinterpretation of the International Code of Zoological Nomenclature. Jones et al. (1992), Baker et al. (2003), and Rice (1998) used P. macrocephalus as the name for the sperm whale. Mead and Brownell (in Wilson and Reeder 1993, 2005) and Nowak (1991) used the name P. catodon.