Mesoplodon bowdoini, also known as Andrew's beaked whales, can be found in cool temperate water such as the Indo-Pacific Ocean. The waters around New Zealand and off the southern coast of Australia are home to this whale.
Biogeographic Regions: indian ocean (Native ); pacific ocean (Native )
Circumpolar distribution in the southern ocean waters north of the Antarctic convergence. Occurs in the southwest Pacific and Indian Ocean between 32oS and 54o30' S, and in the Atlantic Ocean between 36o and 52o S. The majority of recorded strandings have occurred in waters surrounding Australia and New Zealand.
There have been very few sightings of this whale due to its spending little time on the surface. Of the roughly 35 specimens studied, the following is specific to M. bowdoini: indiviuals weigh 2.6 tons at their maximum and at birth the average length is approximately 2 meters. Females grow to an average of 4.6 m., with males growing slightly longer to 4.8 m. The color of males ranges from dark grayish-blue to black, except for the "beak", the tip of the rostrum and lower jaw, which are white in color. Females have more of an off-white beak.
Andrew's whale females or young are distinguished from other Mesoplodon species by their heads, which have a small melon and as a result, slants down dramatically from the body. Also, females and young have short, thick beaks. The dorsal fin of this species is rather small for its body size. This fin is found in the middle of the back, and it is triangular and blunt tipped.
The teeth of males are helpful in identification. Males have two teeth located in the lower jaw within a set of sockets in the middle of the beak. Females also contain these teeth, but they are not visible since they do not erupt through to the surface.
Average mass: 2359 kg.
Range length: 2 to 4.7 m.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
A single pair of teeth is positioned midway between the apex of the beak and the posterior end of the mouth.
Erupted teeth in adult males are covered by gum tissue, with only the tip of tooth exposed. Teeth do not erupt in females or juveniles.
In lateral profile, the anterior margin is weakly sinusoidal (convex proximally, concave distally) and is longer than the strongly convex posterior margin. A denticle is positioned at the top of the anterior edge of the tooth. When the denticle is not excessively worn, it extends well past the antero-dorsal edge of the tooth.
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.
Tooth alveoli of mandible overlap the mandibular symphysis. Separates from Berardius, Ziphius, Tasmacetus, Indopacetus, Hyperoodon, M. grayi, M. europaeus, M. hectori, M. mirus, M. perrini, M. densirostris, M. ginkgodens, M. peruvianus, and M. stejnegeri.
Basirostral groove absent or present as a shallow groove that does not extend past the prominental notch. Separates from M. layardii.
The maxillary prominences rise 15 mm higher than the height of the premaxillaries where the latter passes between the former. Separates from M. bidens.
In dorsal view, the right premaxilla extends slightly posterior beyond the right nasal. Separates from M. traversii.
Antorbital tubercle formed by the maxilla and frontal and is underlain by the jugal and frontal. Separates from M. carlhubbsi.
Melon is relatively flat and defined posteriorly by an indentation at the blowhole. The beak is thick and short with a massive lower jaw that rises prominently on either side of the rostrum about halfway along its length. The mouthline is strongly arched.
Adult males are dark blue-black with a grayish saddle that extends posteriorly from just behind the blowhole for about half the length of the dorsum. The leading edge of the dorsal fin may also be gray. The snout and lower jaws are white or pale gray for up to half the length of the jaw or to just past the teeth. Some individuals have a whitish patch on either side of the forehead at the base of the rostrum. The throat grooves are white or pale gray and the flipper pocket is also lighter in color. Sexually mature males of this species often exhibit scarring from antagonistic sparring. Other oval scars, attributed to the cookie cutter shark, Isistius brasilensis, are present especially in the posterior ventral area of adults.Females have a slate gray dorsum with flanks and belly pale gray to white. There is less white on the beak than in males.
Adult body length ranges between 3.9 to 4.9 m. Recorded maximum body length for adult males and females is 4.6 m and 4.9 m, respectively. Body length at birth is 2.2 m.
Most Likely Confused With:
These animals prefer to forage at depths below the 1000 meter line. This is possibly due to the distribution of squid and other food sources not yet identified. The great depths to which these mammals travel can result in dives that last longer then 45 minutes.
Habitat Regions: temperate
Aquatic Biomes: pelagic ; coastal
Habitat and Ecology
Andrews' beaked whales are assumed to feed primarily on cephalopods, like other members of the genus (Baker 2001). Based on the concentration of stranding records in this area (Baker 2001), the waters around New Zealand may represent an area of concentration for the species.
Mesoplodon bowdoini feeds in deep waters primarily on squid. When squid are not available fish become a secondary source of food.
Animal Foods: fish; mollusks
Primary Diet: carnivore (Piscivore , Molluscivore )
Mesoplodon bowdoini affects the environment by feeding on squid and occasionally fish, which may affect their populations. No relationships with other marine animals are known.
Species Used as Host:
- None known
- None known
- None known
No information is known about predation.
Life History and Behavior
No information is known.
Perception Channels: tactile ; chemical
No information available.
Due to the lack of scarring in M. bowdoini investigators believe that there is no physical competition for partners. Little is known about the mating system of this species.
The only information on the reproductive system of M. bowdoini is from occasional observations of young. The calving season occurs during the summer and autumn.
Breeding season: summer and autumn
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
No specific information is available. As mammals, females nurse their young.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female)
M. bowdoini is protected under the 1972 Marine Mammal Protection Act(MMPA). This established an end to the hunting, harassing, capture or killing of marine mammals in US waters and by US citizens. MMPA also extended the ban on the importation of marine mammals or their products into the country.
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
- 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).
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.
Direct hunting has never been associated with this species. Pervasive gillnet and longline fisheries throughout the species' range raises concern that some bycatch is likely. Even low levels of bycatch might cause unsustainable impacts on this group of naturally rare cetaceans.
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).
Relevance to Humans and Ecosystems
There are no known adverse affects of M. bowdoini on humans.
There are no known positive affects of M. bowdoini on humans. These animals are not significant to the whaling industry.
IUCN Red List Category
Andrew's beaked whale
The Andrew's Beaked Whale (Mesoplodon bowdoini), sometimes known as the Deep-crest Beaked Whale or Splay Toothed Whale, is one of the most poorly known members of a poorly known genus. The specific name bowdoini is in reference to George S. Bowdoin, a donor to the American Museum of Natural History. This species is noteworthy for not having yet been observed in the wild as of 2002.
The body of the Andrew's Beaked Whale is rather robust in comparison with other members of the genus. The melon on the whale is rather low, and the beak is short and thick. The lower jaw is fairly peculiar in that halfway through it rises up significantly with the teeth extending over the rostrum (or "beak"). The head also sometimes has a light patch on the sides, more prominent in the males. Males, overall dark gray to black, have a lighter "saddle" marking in between the blowhole and dorsal fin on their backs. Males also carry scars typical of the genus. Females are slate gray with grayish-white flanks and belly. Cookie cutter shark bites are present in both genders. Females are believed to reach at least 4.9 meters (16 feet) and males 4.5 meters (15 feet). The young are believed to be around 2.2 meters long (7 feet) when born.
The calving season may be during summer and Autumn off New Zealand, otherwise any behavior is completely unknown.
Population and distribution
The Andrew's Beaked Whale lives in the Southern Hemisphere, and its precise range is uncertain. Some 35 stranded specimens have been recorded in Australia and New Zealand, Macquarie Island, the Falkland Islands, Wales and Tristan da Cunha. That range may imply a circumpolar distribution. However, there are no confirmed sightings to back this up.
The Andrew's Beaked Whale has never been hunted and there are no records of it being caught in fish nets.
- MNZ MM002133, collected Spirits Bay, Northland, New Zealand 1992.
- ^ 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 bowdoini. 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
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