Gray's beaked whale

Mesoplodon grayi
Size compared to an average human
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea
Family: Ziphiidae
Subfamily: Hyperoodontinae
Genus: Mesoplodon
Species: M. grayi
Binomial name
Mesoplodon grayi
von Haast, 1876
Gray's beaked whale range

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. 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 mesoplodont), that has upper teeth.[2] In Maori Language, this species is either named as Hakurā or Iheihe.[3]

Taxonomy

The species was first described in 1876 by Julius von Haast, director of the Canterbury Museum, Christchurch, New Zealand. He named it after the British taxonomist John Edward Gray, a zoologist at the British Museum. His description was based on three skulls he had received in May 1875 from a William Hood, Esq., who had retrieved them from three specimens that were part of a group of 28 individuals that had stranded on Waitangi Beach, Chatham Island, in the summer of 1874-75.[4]

Description

Skeleton of Gray's beaked whale.

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.[5] M. grayi are 5.5 to 6.0 m (18.0 to 19.7 ft) long and weigh around 1,100 kilograms (2,400 pounds).[2] 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

Gray's beaked whale is very gregarious. It has a tendency to strand in large groups, once involving 28 individuals. Other strandings involved five to eight animals. The upper teeth may be used in holding prey, but it is not clear why only this species has them.

Gray's beaked whale is said to be the most common species of whale to beach in New Zealand.[6] Two whales that stranded themselves on Opape Beach in the Bay of Plenty, New Zealand, in December 2010 were initially thought to be Gray's beaked whales, but later found to be the incredibly rare spade-toothed whale.[6]

Population and distribution

This species typically lives in the Southern Hemisphere between 30 and 45 degrees, and is typically observed at depths of 2,000 m (6,600 ft).[2] 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, in 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. Gray's beaked whale is included in the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia (Western African Aquatic Mammals MoU) and the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU)

Specimens

References

  1. ↑ 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 grayi". IUCN Red List of Threatened Species. Version 2008. International Union for Conservation of Nature. Retrieved 24 March 2009. Database entry includes a brief justification of why this species is of data deficient.
  2. 1 2 3 Wang, Arthur. "Mesoplodon grayi Gray's beaked whale". Retrieved 18 October 2014.
  3. ↑ http://www.teara.govt.nz/en/te-whanau-puha-whales/page-1
  4. ↑ "On a New Ziphioid Whale. By Julius von Haast, Ph.D. F.R.S., Director of the Canterbury Museum, Christchurch, New Zealand. Communicated by Prof. W. H. Flower, F. R.S." Proceedings of the Zoological Society of London (January, 1876), pp. 7-13.
  5. ↑ Gray's Beaked Whale, Australian Museum. Updated 13 October 2009. Retrieved 13 January 2011.
  6. 1 2 Satherley, Dan (6 November 2012). "World's rarest whale stranded on NZ beach". 3 News NZ.

Bibliography

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