Longman's beaked whales, sometimes known as "tropical bottlenose" or "Indo-Pacific beaked whales," are one of the rarest and least known members of the beaked whale family (Ziphiidae). As adults, Longman's beaked whales can reach estimated lengths of about 20-30 ft (6-9 m); their weight is unknown. Compared to other beaked whales, this species is relatively large.
Longman's beaked whales have a large, robust body with a fairly large, "falcate" "dorsal" fin located far down their back. This species has dark, small, rounded, narrow flippers that fit into a depression on either side of the body. They have a well-defined "melon" (forehead) that is almost perpendicular to their long, tube-shaped beak. A crease may distinguish the melon from the beak. As they grow older, the melon develops into a steeper more bulbous shape that may hang over the beak. Like other beaked whales, they have V-shaped paired throat creases. As scientists have learned more about this species' external appearance and physical description, they have resolved confusion in various at sea sightings.
Longman's beaked whales have a relatively small, low, bushy blow that is usually visible and slightly angled forward. Longman's beaked whales generally have a darker grayish, bronze, brown, or olive coloration that extends from their blowhole and eye down their back, as well as a facial band. The melon and defined "thoracic" patch is lighter in color, sometimes described as "creamy" or pale. The upper jaw of the beak is darker and the lower jaw is lighter. The lower jaw has two conical shaped teeth located at the tip. Adult males have visible, erupted teeth (difficult to see in the field, especially when the mouth is closed), and may have linear and oval-shaped scars (e.g., bites from cookie-cutter sharks and lampreys) along their body.
Many species of beaked whales (especially those in the genus Mesoplodon) are very difficult to distinguish from one another (even when dead). At sea, they are challenging to observe and identify to the species level due to their cryptic, skittish behavior, a low profile, and a small, inconspicuous blow at the waters surface; therefore, much of the available characterization for beaked whales is to genus level only. Uncertainty regarding species identification of beaked whales often exists because of a lack of easily discernable or distinct physical characteristics.
Longman's beaked whales are usually found in tight groups averaging between 10-20 individuals, but occasionally have been seen in larger groups of up to 100 animals. They have sometimes been observed associating with other marine mammals such as pilot whales, spinner dolphins, and bottlenose dolphins. Dives may last from 14-33 minutes and their swimming style has been described as aggressive. This species is commonly misidentified when observed at sea.
The feeding behavior and prey of these cetaceans is generally unknown, but scientists believe it is similar to that of other beaked whales. Beaked whales are known to dive deep to forage for their food, possibly into the "sound channel." The analysis of stomach contents from one stranded specimen implies that cephalopods (e.g., squid and octopus) comprise the majority of the whale's diet.
Nothing is known about the reproduction or lifespan of this species. Due to the rarity, behavior, and infrequent encounters with this species, much of the information available is unreliable. A single young neonate calf was measured at 9.5 ft (2.9 m).
Specimens are recorded from Australia, Somalia, South Africa, the Maldives, Kenya, and Japan. From this information, the full range is currently thought to be the Eastern Pacific through the Indian Ocean to the eastern coast of Africa. Specimens have appeared rarely but widely throughout the Western Pacific and Indian Oceans. Until 2002, this species was only known by two skull specimens, recovered in 1926 and 1968. Flesh samples and live sightings have only been documented very recently.
Biogeographic Regions: indian ocean (Native ); pacific ocean (Native )
- 2005. "Indopacetus pacificus (Longman's beaked whale)" (On-line). IBIS Seamap. Accessed October 14, 2005 at (http://seamap.env.duke.edu/species/tsn/180502).
- Dalebout, M., G. Ross, C. Baker, R. Anderson, P. Best, V. Cockcroft, H. Hinsz, V. Peddemors, R. Pitman. 2003. Appearance, Distribution and Genetic Distinctiveness of Longman's Beaked Whale, Indopacetus Pacificus. Marine Mammal Science, 19/3: 421-462. Accessed November 14, 2005 at http://whitelab.biology.dal.ca/md/Indopacetus_2003.pdf.
Distribution appears to be tropical waters of the Indian and South Pacific oceans.
The distribution of Longman's beaked whales is poorly known and incomplete, but they are believed to occur in the tropical regions of the Indian and Pacific Oceans. In U.S. waters, this species has been sighted in the Hawaiian Exclusive Economic Zone (EEZ) and the equatorial tropical Pacific. Strandings (7 total events) have occurred on the coasts of East (Kenya and Somalia) and South Africa, northern Australia, the Maldives, the Philippines, South Japan, and Sri Lanka. Rare sightings have been documented in the eastern tropical Pacific Ocean. Sightings in the waters surrounding the Maldives archipelago and in the western Indian and Pacific Oceans are more frequent.
Size estimates range from 4 to 9 meters based on extrapolation from skull measurements. A Japanese specimen was 6.5 meters in length, which seems about average based on partial skeletal specimens. Like all beaked whales, this species has a prominent slender beak. Also diagnostic of beaked whales, the throat has two grooves which form a V shape and the fluke is not notched. This whale has a proportionately smaller head than most beaked whales. It is, however, larger overall than most of its close relatives. Longman’s beaked whales are most morphologically similar to Baird’s beaked whales (Beradius bairdii). They may be distinguished, however, because Longman’s beaked whales have a blow hole with concavity oriented forward, toward the anterior of the whale. In Baird’s whales the blow hole tilts toward the posterior. The dorsal fin is larger than that of most beaked whales. The lower jaw contains only a pair of oval teeth, which do not protrude from the jaw. The skin coloration varies between brown and bluish gray and tends to lighten around the flank and head. These whales are sexually dimorphic, with males tending to be larger. Weight estimates could not be found.
Range length: 4 to 9 m.
Sexual Dimorphism: male larger
Other Physical Features: endothermic ; bilateral symmetry
Diagnostic features of the skull and mandible
On the vertex of the dorsal skull the premaxillary bone extends forward of the nasal and frontal bones. Separates from Berardius and Ziphius.
No sulcus exists in middle if the combined antero-dorsal surface of the nasals. Separates from Mesoplodon and Hyperoodon.
Frontal bones occupy an area of the vertex of the skull approximating or exceeding that occupied by the nasal bones. Separates from Berardius, Ziphius, Tasmacetus, and Hyperoodon.
Similar in appearance to Hyperoodon. The medium length beak is distinct from the bulbous forehead. The melon meets the rostrum at an angle of 75 degrees rather than the more severe 90 degrees as seen in Hyperoodon. The mouthline is weakly sinusoidal.
The following description is based on neonate and juvenile color pattern, adult coloration may vary. Posterior to the blowhole, the entire dorsal surface is black, becoming dark gray laterally prior to merging smoothly with the white ventral surface. Posterior to the eye on the lateral surface, the black of the dorsum extends ventrally in a broad band towards the anterior insertion of the flipper, becoming gray at the insertion. A dark band of black extends ventrally from the blowhole to join a black patch surrounding the eye. A small lighter patch is embedded in the area of dark pigmentation posterior to the eye.
Body length range of adult animals is unknown. Recorded maximum body length for an adult female is 5.6 m. Mean body length at birth is unknown.
Most Likely Confused With:
Longman’s beaked whales are pelagic and feed in the deep sea. This conclusion is based on the extreme rarity of sightings and the lifestyles of related species. Also, a specimen was discovered off the coast of Japan in July of 2002. This specimen had distinctive bites from a cookie cutter shark (Isistius brasiliensis). This shark generally lives in the deep sea and its bites are common in deep sea marine life. There is very little data for any of the species in the family Ziphiidae, but one study found that the maximum depth for this related species was 1267 meters.
Habitat Regions: tropical ; saltwater or marine
Aquatic Biomes: pelagic
- Johnson, M., P. Madsen, W. Zimmer, N. Aguilar de Soto, P. Tyack. 2004. Beaked Whales Echolocate on Prey. Proceedings of the Royal Society B: Biological Sciences, 271: S383-S386. Accessed April 18, 2006 at http://www.journals.royalsoc.ac.uk/(plauys452mdttjfuxbnps255)/app/home/content.asp?referrer=contribution&format=3&page=1&pagecount=4.
- Miller, J. 2005. "Animal Diversity Web" (On-line). Accessed October 14, 2005 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Isistius_brasiliensis.html.
Habitat and Ecology
Nothing is known of its feeding habits, except for the stomach contents of a single specimen from Japan (Yamada 2003). These suggested that the species feeds primarily on cephalopods, like other beaked whales.
Water temperature and chemistry ranges based on 5 samples.
Depth range (m): 0 - 0
Temperature range (°C): 25.484 - 28.736
Nitrate (umol/L): 0.050 - 3.535
Salinity (PPS): 33.182 - 34.984
Oxygen (ml/l): 4.613 - 4.716
Phosphate (umol/l): 0.167 - 0.522
Silicate (umol/l): 1.970 - 3.914
Temperature range (°C): 25.484 - 28.736
Nitrate (umol/L): 0.050 - 3.535
Salinity (PPS): 33.182 - 34.984
Oxygen (ml/l): 4.613 - 4.716
Phosphate (umol/l): 0.167 - 0.522
Silicate (umol/l): 1.970 - 3.914
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.
Longman's beaked whales live in generally warm (69.8-87.8° F, 21-31° C), deep (greater than 3,300 ft (1,000 m)), "pelagic" waters of tropical and subtropical regions.
The Japanese specimen’s stomach contents were analyzed, and revealed the beaks of cephalopods.
Animal Foods: mollusks
Primary Diet: carnivore (Molluscivore )
- National Science Museum, Tokyo, 2002. "An Unidentified Beaked Whale Found Stranded in Kagoshima" (On-line). Marine Mammals Information Database. Accessed October 14, 2005 at http://svrsh1.kahaku.go.jp/sendai/indexE.html.
The stomach contents of a Japanese specimen revealed parasitic nematodes. Specifically, Anisakis individuals were extracted. These roundworms are known to parasitize cetaceans.
Ecosystem Impact: creates habitat
- Ritter, J. 2005. "Anisakis simplex" (On-line). Animal Diversity Web. Accessed October 14, 2005 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Anisakis_simplex.html.
Based on the distinctive bites visible on the Japanese specimen, cookie cutter sharks (Isistius brasiliensis) may feed on Longman’s beaked whales. Their large size makes them unlikely prey.
- Isistius brasiliensis (cookie cutter shark)
- Baird, R., P. Clapham, J. Christal, R. Connor, J. Mann, A. Read, R. Reeves, A. Samuels, P. Tyack, L. Weilgart, H. Whitehead, R. Wells, R. Wrangham. 2000. Cetacean Societies. Chicago: University of Chicago Press.
Life History and Behavior
Pelagic beaked whales use echolocation to locate food.
Communication Channels: acoustic
Perception Channels: tactile ; echolocation ; chemical
Natural lifespan of this species is unknown; it has never been kept in captivity.
No information is available on the mating system in this species.
No information is available on reproduction in Longman's beaked whales. In fact, very little information is known about beaked whale (Ziphiidae) reproduction in general. Most toothed whales (Odontoceti), the mammalian suborder that includes beaked whales, have a gestation period of ten to twelve months. Lactation may last from 18 to 24 months, or more. Calving generally occurs every two or three years, and some females may become pregnant while still lactating. Males tend to be larger and reach sexual maturity later.
Breeding interval: There is no information on breeding interval.
Breeding season: There is no information on breeding season in Longman's beaked whales.
Key Reproductive Features: iteroparous ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Like all placental mammals (Eutheria), female beaked whales gestate young for an extended period, and protect and nourish them until they reach independence. Some whales travel in family groups and maintain bonds after young have reached independence. No specific information is available for Longman's beaked whales.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
- Evans, P. 1987. The Natural History of Whales & Dolphins. New York: Facts On File.
Molecular Biology and Genetics
A single pair of teeth is located at the apex of the lower jaw. These incline forward at 45 degrees. These teeth are conical, incline forward at 45 degrees, and do not erupt above the gumline in adult females or juveniles. Female teeth were oval in cross section at their base. Though no adult male specimens have been described it is likely the teeth erupt beyond the gumline and are also oval in cross section.
These teeth do not erupt above the gumline in adult females or juveniles.Though no adult male specimens have been described it is likely the teeth erupt beyond the gumline.
Teeth are conical and oval in cross section.
There is very little information on Longman's beaked whales, they are considered data deficient by the IUCN and are not listed by CITES or the U.S. Endangered Species Act.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: data deficient
IUCN Red List Assessment
Red List Category
Red List Criteria
- 1996Data Deficient(Baillie and Groombridge 1996)
- 1996Data Deficient
- 1996Data Deficient
- 1994Insufficiently Known(Groombridge 1994)
There is no information on trends in the global abundance of this species.
For management purposes, Longman's beaked whales inhabiting U.S. waters have been placed into a single Hawaiian stock. The population of Longman's beaked whales is unknown and no estimates exist. Based on a shipboard line-transect survey from 2002, the best available abundance estimate for the stock that occurs throughout the Hawaiian Islands "EEZ" is 370-770 individuals. There are insufficient data available on current population trends.
It is unknown if military, seismic or other loud noise-producing human activities resulted in the live stranding of a possible mother/calf pair in NE Taiwan (Wang and Yang 2006; Yang et al. 2008). However, “bubble-like lesions” were reported in at least one of these whales by Yang et al (2008). There is some evidence from Sri Lanka for occasional incidental or directed takes of animals identified as ‘bottlenose whales’ which are likely to be Indopacetus (Dayaratne and Joseph 1993).
Evidence from stranded individuals of several similar species of beaked whales indicates that they have swallowed discarded plastic items, which may eventually lead to death (e.g. Scott et al. 2001); this species may also be at risk.
This species, like other beaked whales, is likely to be vulnerable to loud anthropogenic sounds, such as those generated by navy sonar and seismic exploration (Cox et al. 2006).
Predicted impacts of global climate change on the marine environment may affect this species of whale, although the nature of impacts is unclear (Learmonth et al. 2006).
There are no known incidents or reports of this species being exploited by humans such as direct hunting. However, they have been recorded as bycatch in fisheries operating in Sri Lanka. Additionally, various types of fishing gear pose a risk of entangling or interacting with this species. This species of beaked whales may be sensitive to underwater sounds and anthropogenic noise. Anthropogenic noise levels in the world's oceans are an increasing habitat concern, particularly for deep-diving cetaceans like Longman's beaked whales that use sound to feed, communicate, and navigate in the ocean.
Relevance to Humans and Ecosystems
It is unlikely that beaked whales have negative impacts on humans.
Longman's beaked whales are important members of healthy ocean ecosystems.
IUCN Red List Category
Tropical bottlenose whale
The Tropical Bottlenose Whale (Indopacetus pacificus), also known as the Indo-Pacific Beaked Whale and the Longman's Beaked Whale, was considered to be the world's rarest cetacean until recently, but the Spade-toothed Whale now holds that position. The species has had a long history riddled with misidentifications, which are now mostly resolved. A skull found in Mackay, Queensland, Australia provided the initial description, but some authorities insisted on classifying it was a True's Beaked Whale or a female Bottlenose Whale instead of a new species. A whale washed up near Danae, Somalia in 1955 was processed into fertilizer with only the skull remaining, and biologist Joseph C. Moore used it to effectively demonstrate that it was a unique species. However, there was a considerable debate as to whether the whale belonged in the genus Mesoplodon or not. The next major development happened when a paper, available here, had shown that there were actually six remains of the whale, including a complete female with a fetus found in the Maldives in 2000. The other remains consisted of a skull from Kenya from before 1968, and two juveniles from South Africa in 1976 and 1992 respectively. The paper used DNA analysis to show that the Tropical Bottlenose Whale is likely to be an independent genus, but information on other species was too lacking to establish any concrete phylogeny. The external physical appearance was also revealed, and a firm connection was established with the mysterious Tropical Bottlenose Whales sighted in the Indian and Pacific Oceans. During the publication of the paper, a specimen originally identified as a Giant Beaked Whale washed up in Kagoshima, Japan in July 2002. Another specimen claimed to be a Tropical Bottlenose Whale which washed up in South Africa in August 2002 is likely a misidentified Cuvier's Beaked Whale.
The Longman's Beaked Whales look rather similar to both Mesoplodont Beaked Whales and Bottlenose Whales, which led to a great deal of taxonomic confusion. The Maldives female had a robust body like the Bottlenose Whales, although this may be a distortion since the less decomposed female specimen from Japan had a laterally compressed body typical of Mesoplodonts. The juvenile specimens have a very short beak similar to a Bottlenose Whale, but the adult females seen so far have had rather long beaks sloping gently into a barely noticeable melon organ. Additionally, the dorsal fins of adult specimens seem unusually large and triangular for Beaked Whales, whereas in juveniles they are rather small and swept back. An adult male specimen has yet to wash up, but sightings of the Tropical Bottlenose Whale indicate that they have a rather bulbous melon, two teeth located towards the front of the beak, as well as the scars from fighting with the teeth. Scars from cookiecutter sharks are also rather common on the whale. The rather unusual coloration of the juveniles helped connect the Longman's Beaked Whale to the Tropical Bottlenose Whale; both of them have a dark back behind the blowhole which quickly shades down to a light gray and then white. The blackness from the back extends down to the eye of the whale except for a light spot behind the eye, and then continues on in a line towards the flipper, which is also dark. Dark markings are also present on the tip of the beak and rostrum. The females have a simpler coloration; the body is typically grayish except for a brown head. It appears that the coloration is rather variable in this species. The female specimen from the Maldives was 6 meters (20 feet) in length with a 1 meter (3 foot) fetus, and the Japanese female was 6.5 meters (22 feet) in length. Reports of Tropical Beaked Whales put them at even larger length in the 7-8 meter (23–26 foot) range, which is larger than any Mesoplodon and more typical of a Bottlenose Whale. No weight estimation or reproductive data is known.
Population and distribution
Carcasses indicate the species ranges across the Indian Ocean from Southern and Western Africa to the Maldives, with a Pacific range extending from Australia up to Japan. However, if the sightings of the Tropical Beaked Whale are taken into account, the range of this whale is extensively larger. They have been sighted from the Arabian Sea to the western shore of Mexico. They have also been seen in the Gulf of Mexico, which would indicate that they are present in the tropical Atlantic Ocean as well. The most frequent observations have occurred off the coasts of Hawaii. While no specimens have washed up from Hawaii, they are apparently rather common; a 2002 survey estimates that there were 766 animals. No other population estimates exist for other locales.
Tropical Bottlenose Whale observations indicate that they travel in larger groups than any other local species of beaked whale. The size of the pods range from the tens up to 100, with 15 to 20 being fairly typical, and the groups appear very cohesive. Their pods are frequently associated with other species, such as Short-finned Pilot Whales and Bottlenose Dolphins. Tropical Bottlenose Whales have been known to breach the surface, and they normally have visible, but short, blows. Their dives have been clocked at 18 to 25 minutes.
There are no records of the whale being hunted, caught in fishing gear, or affected by Navy Sonar. Due to their rather uncommon nature, their conservation status is unknown.
- Longman's Beaked Whale Hawaiian Stock. Revised 3/15/05. Available: here
- Appearance, Distribution, and Genetic Distinctiveness of Longman's Beaked Whale, Indopacetus pacificus. Dalebout, Ross, Baker, Anderson, Best, Cockcroft, Hinsz, Peddemors, and Pitman. July 2003, Marine Mammal Science, 19(3):421–461. Available: here
- National Audubon Society Guide to Marine Mammals of the World Reeves et al., 2002. ISBN 0-375-41141-0.
- Sightings and possible identification of a bottlenose whale in the tropical Indo-Pacific: Indopacetus pacificus? Pitman, Palacios, Brennan, Brennan, Balcomb and Miyashita, 1999. Marine Mammology Science Vol 15, pps 531-549.
- Encyclopedia of Marine Mammals Robert L. Pitman, 1998. ISBN 0-12-551340-2
- Whales, Dolphins and Porpoises Carwardine, 1995. ISBN 0-7513-2781-6
- More skull characters of the beaked whale Indopacetus pacificus and comparative measurements of austral relatives J.C. Moore 1972. Field Zoology. Vol 62 pps 1-19.
- Relationships among the living genera of beaked whales with classifications, diagnoses and keys J.C. Moore 1968. Field Zoology. Vol 53, pps 206-298.
- ^ Taylor, B.L., Baird, R., Barlow, J., Dawson, S.M., Ford, J., Mead, J.G., Notarbartolo di Sciara, G., Wade, P. & Pitman, R.L. (2008). Indopacetus pacificus. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 24 March 2009. Database entry includes a brief justification of why this species is of data deficient.
Did you know?
· Longman's beaked whales are one of the rarest cetaceans. Until fairly recently, this species was only known and described from two skulls found on beaches in Africa (in 1955) and Australia (in 1882, but described by Longman in 1926).
· Longman's beaked whales were originally placed in the Mesoplodon genus (given the name Mesoplodon pacificus in 1926), but due to differences in features of the skull they have been reclassified as their own genus, Indopacetus.