Gray's Beaked Whale (Mesoplodon grayi), sometimes known as Haast's Beaked Whale, the Scamperdown Whale, or the Southern beaked whale, is one of the better-known members of the genus Mesoplodon. The scientific name refers to John Edward Gray, a zoologist at the British Museum. This species is fairly gregarious and strands relatively frequently for a beaked whale. It is notable for being the only beaked whale, other than Shepherd's Beaked Whale (not a Mesoplodon), that has numerous teeth.

Description

Gray's Beaked Whale is a fairly slender member of the genus. The melon on the whale bulges towards the blowhole and slopes down towards the beak. The beak itself is very long and pointed for a beaked whale, and has a relatively straight mouth line. In both sexes there are 17–22 rows of small teeth located towards the back of the mouth which barely protrude past the gum. In males, there are two small, triangular teeth present halfway down the mouth. The overall coloration is dark on top and light below, and both sexes have a white beak. Females are lighter on top and have additional white marking near the genitals. Adult males often carry linear scars that probably result from fighting, and both males and females may display circular scars from cookiecutter shark bites.^[2] Females reach at least 5.3 meters (17 feet 6 inches) whereas males reach 5.7 meters (19 feet) and weigh around 1100 kilograms (2400 pounds). They are believed to be around 2.4 meters (7 feet 10 inches) long when born.

Behavior

An adult female, one of five Gray's beaked whales stranded at Port Waikato, New Zealand.

The Gray's beaked whale is very gregarious. It has a tendency to strand in large groups, once involving 20 individuals. Other strandings involved five to eight animals. The upper teeth may be used in holding prey, but it not clear why only this species has them.

Population and distribution

This species typically lives in the Southern Hemisphere between 30 and 45 degrees. Many strandings have occurred off New Zealand, but others have happened off Australia, South Africa, South America, and the Falkland Islands. This species has been sighted in groups off the coast of Madagascar and in the Antarctic area. Oddly, one specimen stranded off the Netherlands, on a different Hemisphere and several thousand miles away from all other strandings. No population estimates exist, but they are believed to be rather common.

Conservation

These whales have not been hunted deliberately and they have not been entangled in fishing gear.

Specimens

• MNZ MM002134 Gray's Beaked Whale Mesoplodon grayi, collected Black Reef, Cape Kidnappers, Hawke Bay, New Zealand, 18 March 1993.

References

Bibliography

Cetaceans portal

• Encyclopedia of Marine Mammals. Edited by William F. Perrin, Bernd Wursig, and J.G.M Thewissen. Academic Press, 2002. ISBN 0-12-551340-2
• Sea Mammals of the World. Written by Randall R. Reeves, Brent S. Steward, Phillip J. Clapham, and James A. Owell. A & C Black, London, 2002. ISBN 0-7136-6334-0

Mesoplodont whales are fourteen species of whale in the genus Mesoplodon, making it the largest genus in the cetacean order. Two species were described as recently as 1991 (Pygmy Beaked Whale) and 2002 (Perrin's Beaked Whale), and marine biologists predict the discovery of more species in the future. They are the most poorly known group of large mammals. The word mesoplodon comes from the Greek meso- (middle) - hopla (arms) - odon (teeth), and may be translated as 'armed with a tooth in the centre of the jaw'.

Species

English name (most common first), Latin name:

• Sowerby's Beaked Whale M. bidens
• Andrews' Beaked Whale M. bowdoini
• Hubbs' Beaked Whale M. carlhubbsi
• Blainville's Beaked Whale M. densirostris
• Gervais' Beaked Whale M. europaeus
• Ginkgo-toothed Beaked Whale M. ginkgodens
• Gray's Beaked Whale M. grayi
• Hector's Beaked Whale M. hectori
• Layard's Beaked Whale M. layardii (a.k.a. Strap-toothed_Whale)
• True's Beaked Whale M. mirus
• Perrin's Beaked Whale M. perrini
• Pygmy Beaked Whale M. peruvianus
• Stejneger's Beaked Whale M. stejnegeri
• Spade-toothed Whale M. traversii
• †Mesoplodon longirostris

Longman's Beaked Whale (also known as the Indo-Pacific Beaked Whale) is also sometimes classed in the Mesoplodon genus. However, all recent authorities follow the lead of Joseph Curtis Moore who in the 1960s put it in its own genus - Indopacetus.

Physical description

Beaked whales are typically medium- to large-sized for toothed whales, 3 to 6 meters in length, but diminutive when compared with Bottlenose Whales and Giant Beaked Whales. The females are the same size or larger than males in every species, but the males typically have a bolder coloration and a unique dentition. The lower jaw often forms a huge arch in some species, sometimes extending above the rostrum in a shape comparable to a playground slide. Every species has large (sometimes tusk-like) teeth of variable size, shape, and position. Gray's Beaked Whale is the exception and has numerous small and possibly functional teeth in the lower jaw. The males of most species are covered in scars from the teeth of other males. Both sexes often have bites from cookie-cutter sharks. The dorsal fin is rather small and far between two-thirds and three-quarters down the back of the animal. Information on longevity and lactation is not existent, and information on gestation is nearly so.

Behavior

Most species are very rarely observed, and little is known about their behavior. They are typically found in groups, possibly segregated between sexes. Some species are so uncommon that they have yet to be observed alive. On the surface they are typically very slow swimmers and do not make obvious blows. They have never been observed raising their flukes above the water either. They are all very deep divers, and typically feed entirely on squid.

Conservation

The Mesoplodonts are completely unknown as far as population estimates are concerned. They have been hunted occasionally by the Japanese, but never directly. They are also accidentally captured in drift nets. It is not known what effect this has on the population.

References

Cetaceans portal

• Encyclopedia of Marine Mammals. Edited by William F. Perrin, Bernd Wursig, and J.G.M Thewissen. Academic Press, 2002.
• Sea Mammals of the World. Written by Randall R. Reeves, Brent S. Steward, Phillip J. Clapham, and James A. Owell. A & C Black, London, 2002.