Mammal Species of the World
Mesoplodon hectori is distributed in oceans throughout the Southern Hemisphere.
Biogeographic Regions: ethiopian (Native ); neotropical (Native ); australian (Native )
Previously, it was supposed that this species may also be vagrant in southern California, where there were several strandings and a possible sighting from 1975 to 1979 (Mead 1981, Mead and Baker 1987, Rice 1998). However, the California specimens were recently recognised as a new species Mesoplodon perrini, which is found in the eastern North Pacific (Dalebout et al. 1998; Dalebout et al. 2002).
Occurs in the South Pacific, South Atlantic and Indian oceans below 40oS. It apparently frequents more southernly (colder) waters.
Hector's beaked whales can be distinguished from other species of Mesoplodon by the shape of the mandibles, the shape of the rostrum, and the position of its single pair of teeth in the lower jaw. This species has a narrower premaxillary crest than other Mesoplodon species. The teeth are triangular and positioned near the tip of the lower jaw. Other species, such as Mesoplodon mirus and Mesoplodon pacificus also have teeth close to the tip of the jaw, but the morphology of their teeth differs from that of M. hectori in that M. mirus has smaller and more conical teeth than M. hectori, and the teeth of M. pacificus are sloped forward at a 45° angle. The teeth of M. hectori are not sloped forward in this manner. The dorsal fin is small and rounded and the tail flukes are straight-edged and broad.
This species is the second smallest of all beaked whales, second only to pygmy beaked whales (Mesoplodon peruvianus). No subspecies or polymorphisms of M. hectori are known to exist. Males and females do not differ in size, but they do have different color patterns. Dorsally, males are dark grey with a lighter grey ventral zone. Females, on the other hand, are light grey dorsally and white ventrally. Both males and females tend to have white lower jaws.
Additionally, while males have a single pair of teeth (tusks) in the lower jaw, females and juveniles usually do not. This dimorphism is consistent with other species of Mesoplodon. Males of this species tend to have extensive scarring as a result of aggressive intrasexual encounters where teeth are used to establish breeding hierarchies. Males also tend to have increased ossification of the rostrum, which may allow them to aggressively contact each other with the tops of their rostra without risking damage to the rostrum. Because so few specimens have been found alive, there is virtually no information on the average mass or basal metabolic rate of these animals. However, one study suggests that M. hectori can reach up to 800 kg.
Range mass: 800 (high) kg.
Range length: 4.5 (high) m.
Average length: 4 m.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes colored or patterned differently; ornamentation
A single pair of large teeth are positioned at apex of the mandible. Teeth incline anteriorly.
Nearly all of erupted teeth in adult males are exposed above the gumline. Teeth do not erupt in female or juveniles.
The lateral profile of the exposed tooth is shaped like an isosceles triangle. Instead of being smoothly convex the anterior margin has three flattish areas between the denticle and root. The anterior margin is also shorter than the posterior margin. The denticle is on the dorso-anterior edge of the tooth. The angle formed by the denticle is between 85 to 90 degrees.
Diagnostic features of the skull and mandible
On the vertex of the dorsal skull the premaxillary bone extends forward of the nasal and frontal. Separates from Berardius and Ziphius.
A sulcus (groove) running along the middle of the combined surfaces of the nasal bones so depresses their middle that it is the lateral portion of each nasal bone that reaches farthest forward on the vertex. Separates from Tasmacetus and Indopacetus.
When the skull is upright and the long axis of the anterior half of the beak is horizontal, a horizontal plane transecting the summit of either maxillary prominence transects the mesethmoid bone. Separates from Hyperoodon.
ooth alveoli of mandible are positioned at the apex of the mandible.Separates from M. bidens, M. bowdoini, M. carlhubbsi, M. densirostris, M. europaeus, M. grayi, M. ginkgodens, M. layardi, M. peruvianus, M. stejnegeri, and M. traversi.
The space between the nasals is wide with parallel sides and "U" shaped. Separates from M. perrini.
Maxilla and lacrimal comprise bones of antorbital tubercle. Separates from M. mirus.
Forehead slopes steeply over a slightly bulging melon. The beak is short with a relatively straight mouthline.
Descriptions of coloration in M. hectori are lacking. The main accounts in the literature are based on specimens of that have subsequently been attributed to a separate species, M. perrini. Previous accounts describe an animal that is dark dorsally and pale ventrally.
Adult body length ranges between 4 to 5 m. Recorded maximum body length for adult males and females is 5 m and 4.3 m, respectively. Length at birth is 2 m.
Most Likely Confused With:
Size in North America
Range: up to 4.3 m males; up to 4.4 m females
Mesoplodon hectori is found in pelagic oceanic waters in the Southern Hemisphere, primarily in cold temperate waters between 35° South and 55° South. Beached specimens have been found in Argentina, the Falkland Islands, South Africa, Chile, New Zealand, and Tasmania. One beached specimen was found 80 km north of Rio Grande in Southern Brazil, the northernmost sighting of this whale. These whales may undergo a slight seasonal migration to cooler waters during summer months. They seem to prefer colder shelf-edge or canyon habitats. They can dive to a depth of 5.75 km but, on average, they dive to a depth of 3.5 km.
Range depth: 5.75 (low) km.
Average depth: 3.5 km.
Habitat Regions: temperate ; saltwater or marine
Aquatic Biomes: pelagic
Habitat and Ecology
Little is known of the diet, but Hector's beaked whales are known to feed on squid, like most other beaked whales.
Although little is known about the specific feeding behavior of Mesoplodon hectori, researchers suggest that Mesoplodon species are piscivores. Among the genera of beaked whales (g.Hyperoodon>, Mesoplodon, and Ziphius), Mesoplodon species tend to eat the most fish – and their prey tends to be smaller than those of the other two genera. Mesoplodon species also eat cephalopods. Most prey is benthic or benthopelagic, meaning that it lives at or near the ocean floor, usually between 200 and 2000 meters in depth. Mesoplodon species are generalist feeders, in that they eat whatever prey is locally abundant.
Mesoplodon hectori is most likely a suction feeder like other species in the genus. Powerful muscles at the back of the tongue work in tandem with pleated throat grooves to allow the mouth to distend and create a vacuum that sucks prey into the mouth, prey that is then swallowed whole. Some scholars believe that Mesoplodon suction feeding is an adaptation to eating squid in particular.
Like all species of Mesoplodon, this species most likely uses echolocation to locate prey. When searching for food, Mesoplodon emits high-frequency clicks to detect squid and other small marine creatures. A study of foraging Mesoplodon revealed that these beaked whales tend to click only at depths between 200 and 1267 meters and they click continuously once at those depths. Even though specific studies with M. hectori have not been conducted, it is likely that this species uses echolocation to forage in a similar fashion to other members of Mesoplodon.
Animal Foods: fish; aquatic crustaceans; other marine invertebrates
Primary Diet: carnivore (Piscivore , Molluscivore )
Beaked whales are some of the most numerous cetaceans in their geographic range and are important “apex” predators as a result. However, little is known about the specific ecological role Mesoplodon hectori plays in its marine ecosystem.
Hector's beaked whales may play host to a number of parasites. In 2005, a female specimen was found to have a species of Sarcocystis in her skeletal muscle as well as a species of Tetrabothrius and a species of Bolbosoma in her intestinal tract. A beached male concurrently analyzed was found to have Braunina cordiformis in his stomach. Both specimens also had a species of Anisakis in their digestive tracts. Neither individual died from these parasites, and researchers concluded that the presence of the stomach parasites, presumably acquired through consuming intermediary hosts, is most likely common and non-fatal for M. hectori.
Species Used as Host:
- No research has been conducted to determine if Mesoplodon hectori uses any other species as a host.
- No research has been conducted to determine if Mesoplodon hectori is mutualist with any other species.
- Braunina cordiformis
Little is known about the predators or anti-predator adaptations of Mesoplodon hectori. Some research suggests that Orcinus orca may occasionally prey on this species, but no definitive evidence exists to verify this claim.
Life History and Behavior
Echolocation has been identified as a feeding behavior of this species, but high-frequency echolocation of up to 120 Hz may also be used for social communication. Mesoplodon hectori may also use non-echolocating sounds ranging from 1 to 16 kHz to communicate with other individuals. Other species of beaked whales whistle in a way that researchers suggest serves a social function, although the nature of that social function is not yet clear. Although the group size of M. hectori is still unclear, the presence of both high-frequency echolocation and non-echolocating sounds may bolster the hypothesis that this species is not a completely solitary species but instead lives in small groups where communication is necessary.
Communication Channels: acoustic
Perception Channels: visual ; tactile ; acoustic ; ultrasound ; echolocation ; chemical
Because fewer than 30 specimens of Mesoplodon hectori have been found – and of those, only a few found alive – there’s very little information on longevity. However, based on longevity data from other members of the genus, this species may be a long-lived species, living at least to its early 30's and potentially even longer. Other than these speculations, there is no research on longevity in the wild for this species. No attempts to keep M. hectori in captivity have been documented.
Little information is known about their mating system. Scholars suggest that the mating behaviors of beaked whales may be similar to those of other toothed whales. Because toothed whales tend to live in small groups that occupy thousands of square miles of ocean. When individuals of the opposite sex do come across each other, they take advantage of the meeting by emitting a series of physical and hormonal cues to indicate readiness to breed. However, no research exists to suggest that Mesoplodon hectori follows these same mating patterns.
Researchers have documented that beaked whales, including species of Mesoplodon, use their teeth to defend their mates and territory from other males and to establish breeding hierarchies. Although little is known about the specific mating system of Mesoplodon hectori, the presence of scarring on some beached male specimens suggests that males may also engage in this intrasexual aggression, most likely to defend females and territories.
Although little information exists about the reproductive behavior of Mesoplodon hectori, studies of other Mesoplodon species suggests that breeding most likely occurs between October and December. Calves of other Mesoplodon species are usually born in February or March in areas much shallower than their normal habitats. Hector's beaked whales may follow this breeding pattern. Mothers most likely give birth to a single calf. Mesoplodon species in general have gestational periods averaging 12 months, but virtually no information exists as to how long the specific gestation period is for M. hectori. At birth, calves are 190 to 202 centimeters long. Research on other Mesoplodon species suggests that sexual maturity may occur anywhere from 9 to 12 years old for females and males, but no specific information exists for this species. At the time of weaning, juveniles are estimated to be about 3 meters in length. Other reproduction information is not reported in the literature.
Breeding interval: Mesoplodon hectori has an interbirth period of at least three to four years, giving it a relatively slow reproductive capacity.
Breeding season: No information exists as to the specific breeding season of this whale, but studies of other members of the genus suggests that breeding may occur between October and December.
Average number of offspring: 1.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
All cetaceans share a similar style of parental investment. The mother nurses the young. If she lives in a group, the mother and her entire pod teach the young how to avoid predators and to feed. However, because Mesoplodon hectori is thought to be a relatively solitary species, the mother may be the only adult in charge of socializing her young. No other information about parental investment in M. hectori has been documented.
Parental Investment: precocial ; female parental care ; 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)
Even though there have been only a handful of sightings of Mesoplodon hectori at sea, this species does not classify as vulnerable, threatened, or endangered on any of the major lists. Individuals of many Mesoplodon species have gotten entangled in offshore fishing nets over the last twenty years, and M. hectori may be at risk for entanglement as well.
US Federal List: no special status
CITES: appendix ii
State of Michigan List: no special status
IUCN Red List Assessment
Red List Category
Red List Criteria
- 1996Data Deficient
- 1994Insufficiently Known(Groombridge 1994)
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).
As a temperate water species, Hector’s beaked whale may be vulnerable to the effects of climate change as ocean warming may result in a shift or contraction of the species range as it tracks the occurrence of its preferred water temperatures (Learmonth et al. 2006). The effect of such changes in range size or position on this species is unknown.
Evidence from stranded individuals of several similar species 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.
Relevance to Humans and Ecosystems
There are no documented cases of negative interactions between humans and Mesoplodon hectori.
Some specimens of Mesoplodon hectori may have been captured by opportunistic whalers over a hundred years ago. However, their general elusiveness means that few, if any, modern incidences of human exploitation have been reported because few people have encountered this species alive.
Positive Impacts: body parts are source of valuable material; research and education
IUCN Red List Category
Hector's beaked whale
Hector's Beaked Whale, Mesoplodon hectori, is a small Mesoplodont living in the Southern Hemisphere. This whale is named after Sir James Hector, a founder of the colonial museum in Wellington, New Zealand. Some specimens that have washed up and been sighted in California that were once thought to belong to this species have subsequently been shown through analysis of mtDNA and detailed morhological examination to be a new species, Perrin's Beaked Whale (Dalebout et al. 2002). As of 2007, they have yet to be seen alive in the wild.
Note that some data supposedly referring to this species, especially juveniles and males, turned out to be based on the misidentified specimens of Perrin's Beaked Whale - especially since the adult male of Hector's Beaked Whale was only more recently described. See Perrin's Beaked Whale for specimen data. Dalebout et al. (2002) specifically list Mead (1981), Mead (1984), Mead & Baker (1987), Mead (1989), Baker (1990), Jefferson et al. (1993), Mead (1993), Carwardine (1995), Reeves & Leatherwood (1994), Henshaw et al. (1997) and Messenger & McQuire (1998) as erroneously attributing data from the new species to Hector's Beaked Whale.
Reaching a maximum length of about 4.2 meters (1.9 m when born), and with an estimated weight of about 1 tonne (1.032 tons), Hector's is one the smallest of the beaked whales. It is known from only a few stranded animals. Hector's Beaked Whales are dark greyish-brown dorsally, paler ventrally and may have white or pale lower jaws. The melon, which is not very prominent, slopes quite steeply to the short beak. Adult males have a pair of flattened, triangular teeth near the tip of the lower jaw. As with most other beaked whales, the teeth do not erupt in females. The dorsal fin is triangular to slightly hooked, small, and rounded at the tip. The leading edge of the dorsal fin joins the body at a sharp angle.
With only two probable sightings, there is little information on the behavior of this whale. This species may be unusual for a Mesoplodon because, in both sightings, one of the animals seemed inquisitive and actually approached the boat. Body scarring suggests there may be extensive fighting between males, which is common in beaked whales.
Nothing is known about breeding in this species. Sightings are rare due to their deep-ocean distribution, elusive behaviour and possible low numbers.
Population and Distribution
Hector's Beaked Whale has a circumpolar distribution in cool temperate Southern Hemisphere waters between approximately 35° and 55°S. Most records are from New Zealand, but there are also reports from Falkland Sound, Falkland Islands, Lottering River, South Africa, Adventure Bay, Tasmania, and Tierra del Fuego, in southern South America.
This species has never been hunted at all, and has not entangled itself in fishing gear. Most sightings of the whale have been stranded specimens on beaches, particularly in New Zealand.
- MNZ MM001834 - 16 July 1980; Kaikoura, New Zealand
- ^ 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). Mesoplodon hectori. 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.
- Baker, Alan N. (1990): Whales and dolphins of New Zealand and Australia: An identification guide. Victoria University Press, Wellington.
- Carwadine, M. (1995): Whales, dolphins and porpoises. HarperCollins, London.
- Dalebout, Merel L.; Mead, James G.; Baker, C. Scott; Baker, Alan N. & van Helden, Anton L. (2002): A New Species of Beaked Whale, Mesoplodon perrini sp. n. (Cetacea: Ziphiidae), Discovered Through Phylogenic Analysis of Mitochondrial DNA Sequences. Marine Mammal Science 18(3): 577-608. doi:10.1111/j.1748-7692.2002.tb01061.x PDF fulltext
- Henshaw, M.D.; Leduc, R.G.; Chivers, S.J. & Dizon, A.E. (1997): Identification of beaked whales (family Ziphiidae) using mtDNA sequences. Marine Mammal Science 13(3): 487-495. doi:10.1111/j.1748-7692.1997.tb00656.x (HTML abstract)
- Jefferson, T.A.; Leatherwood, S. & Webber, M.A. (1993): FAO species identification guide: Marine mammals of the world. United States Environment Programme & Food and Agriculture Organization of the United Nations (FAO), Rome. PDF fulltexr
- Mead, James G. (1981): First records of Mesoplodon hectori (Ziphiidae) from the northern hemisphere and a description of the adult male. Journal of Mammalogy 62(2): 430-432. doi:10.2307/1380733 (First page image)
- Mead, James G. (1984): Survey of reproductive data for the beaked whales (Ziphiidae). Report of the International Whaling Commission Special Issue 6: 91-96.
- Mead, James G. (1989): Beaked whales of the genus Mesoplodon. In: Ridgway, S.H. & Harrison, R. (eds.): Handbook of marine mammals Vol.4: 349-430. Academic Press, London.
- Mead, James G. (1993): The systematic importance of stomach anatomy in beaked whales. IBI Reports 4: 75-86.
- Mead, James G. & Baker, Alan N. (1987): Notes on the rare beaked whale, Mesoplodon hectori (Gray). Journal of the Royal Society of New Zealand 17: 303-312.
- Messenger, S.L. & McQuire, J.A. (1998): Morphology, molecules and the phylogenetics of cetaceans. Systematic Biology 47(1): 90-124. doi:10.1080/106351598261058 (HTML abstract)
- Perrin, William F.; Wursig, Bernd & Thewissen, J.G.M (eds.) (2002): Encyclopedia of Marine Mammals. Academic Press. ISBN 0-12-551340-2
- Reeves, Randall R. & Leatherwood, S. (1994): Dolphins, porpoises and whales: 1994-98 Action plan for the conservation of cetaceans. IUCN, Gland, Switzerland. ISBN 2-8317-0189-9
- Reeves, Randall R.; Steward, Brent S.; Clapham, Phillip J. & Owell, James A. (2002): Sea Mammals of the World. A & C Black, London. ISBN 0-7136-6334-0