Mesoplodon layardii

Mesoplodon layardii, Photo: Michael Lahanas

Cladus: Eukaryota
Supergroup: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Classis: Mammalia
Subclassis: Theria
Infraclassis: Placentalia
Superordo: Cetartiodactyla
Ordo: Cetacea
Subordo: Odontoceti
Infraordines: Physeterida
Superfamiliae: Ziphioidea
Familia: Ziphiidae
Subfamiliae: Hyperoodontinae
Genus: Mesoplodon
Species: Mesoplodon layardii

Name

Mesoplodon layardii (Gray, 1865)

References

* Mesoplodon layardii on Mammal Species of the World.
Mammal Species of the World: A Taxonomic and Geographic Reference, 2 Volume Set edited by Don E. Wilson, DeeAnn M. Reeder
* Mammal Species of the World, A Taxonomic and Geographic Reference, 3rd edition, 2005 ISBN 0801882214

Vernacular names
Internationalization
日本語: ヒモハクジラ
Türkçe: Uzun dişli gagalı balina

The strap-toothed whale (Mesoplodon layardii), also known as the Layard's beaked whale or the long-toothed whale is a large mesoplodont with some of the most bizarre teeth of any mammal. The common and scientific name was given in honor of Edgar Leopold Layard, the curator of the South African Museum who prepared drawings of a skull and sent them to the British taxonomist John Edward Gray, who described the species in 1865.[2]

Description

The overall body shape of the strap-toothed whale is fairly typical for a mesoplodont, except for the large size. Male specimens have large and peculiar teeth even for the genus; they are large straps, sometimes over 30 centimeters (1 foot) in length, which grow over the jaw at a 45 degree angle and nearly close it. The teeth also have dorsally projecting denticles, and are still apparently used for fighting. Barnacles quite frequently are found on the teeth, as well. Why the species would grow teeth that severely cut back on the size of prey it can consume is quite uncertain. The melon is somewhat bulbous, and blends in to the beak shortly before the strap teeth. The beak itself is fairly long, with a relatively straight mouthline. The coloration of this species is also unusual for a mesoplodont, since it is rather bold; most of the body is black except for a white areas on the front of the beak, the throat, an area behind the head in a shape reminiscent of a cape, and near the genitals. Juveniles do not have this coloration and are typically dark above and light below. Scars and cookie cutter shark bites are also present. Males can reach around 5.9 meters (19 feet 6 inches), whereas females reach 6.2 meters (20 feet) and likely weigh around 1000-1300 kilograms (2200-2900 pounds), indicating they are probably the largest species in the genus. Newborn calves may be up to 2.8 meters (9 feet) in length.

Population and distribution

The Strap-toothed whale is distributed in cool temperate waters of the Southern Hemisphere between 30° S and the Antarctic Convergence. It may occur south of 38° S year-round moving north of 38° S seasonally.[3] As of 1991, there are about 140 records (nearly all strandings) of this species from New Zealand (50, including one sighting), Australia (over 40), southern Africa (about 40), southern Argentina and Tierra del Fuego (10), southern Chile (4), Falkland Islands (3), and Uruguay (1).[4] Strandings have also been reported from Heard Island, the Kerguelen Islands, and Brazil. More recently one individual was seen breaching between the South Orkney Islands and South Georgia.[5]

Behavior

Nothing is known about social organization, and this species is a squid eater. Males have a gape half the size of females and juveniles, limiting their squid to those weighting 100 grams (3.5 ounces) and less.

Conservation

This species has never been hunted or entangled in fishing gear. It is believed to be in a rather safe position compared with other mesoplodonts.

References

^ 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 layardii. 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
^ Reeves, R., Stewart, B., Clapham, P. & Powell, J. (2002). Guide to Marine Mammals of the World. New York: A.A. Knopf. p. 292. ISBN 0-375-41141-0.
^ Shirihai, H. and Jarrett, B. (2006). Whales, Dolphins and Other Marine Mammals of the World. Princeton Field Guides. p. 142. ISBN 0-61-12757-2.
^ Klinowska, M. (1991). Dolphins, Porpoises and Whales of the World: The IUCN Red Data Book. Cambridge, U.K.: IUCN.
^ Jefferson, Thomas, Marc A. Webber, and Robert L. Pitman (2008). Marine Mammals of the World: A Comprehensive Guide to their Identification. London: Academic.


Encyclopedia of Marine Mammals. Edited by William F. Perrin, Bernd Wursig, and J.G.M Thewissen. Academic Press, 2002. ISBN 0-12-551340-2

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