True's Beaked Whale


True's Beaked Whale

Taxobox
name = True's Beaked Whale
status = DD
status_system = iucn2.3



image_caption = Size comparison against an average human
regnum = Animalia
phylum = Chordata
classis = Mammalia
ordo = Cetacea
subordo = Odontoceti
familia = Ziphidae
genus = "Mesoplodon"
species = "M. mirus"
binomial = "Mesoplodon mirus"
binomial_authority = True, 1913
range_


range_map_caption = True's Beaked Whale range

The True's Beaked Whale ("Mesoplodon mirus") is a relatively conventional species of Mesoplodont. The common name is in reference to Frederick W. True, a curator at the United States National Museum (now the Smithsonian). There are two distinct populations in the Atlantic and Indian ocean (this species is absent in the tropics) and subspecies may need to be established.

Physical description

This whale has a fairly normal Mesoplodont body, except that it is more rotound in the middle and more tapering towards the ends. The two distinctive teeth on the males are relatively small and set on the very end of the beak. The melon is rather bulbous, and leads into a fairly short beak. There is a crease behind the blowhole, and a sharp dorsal ridge on the back near the dorsal fin. The coloration is gray to brownish gray on the back which is lighter below, and notably darker on the "lips", around the eye, and near the dorsal fin. There is sometimes a dark blaze between the head and dorsal fin as well. One female in the Southern Hemisphere was bluish black with a white area between the dorsal fin and tail as well as a light gray jaw and throat, as well as black speckling. Scars from fighting and cookiecutter sharks are present on males. This species reaches around 5.3 meters (17 feet 6 inches) with the females weighing 1400 kilograms (3000 pounds) and the males weighing 1010 kilograms (2200 pounds). They are around 2.2 meters (7 feet) long when born.

Behavior

They have been seen in rather small groups, and are believed to be squid eaters. It is believed that when a whale is injured, another whale stays with it to nurse it. Other than that, little else is known.

Population and distribution

One population, possibly genetically distinct, lives in the Northern Hemisphere and has stranded from Nova Scotia in the western Atlantic to Ireland in the eastern Atlantic and as far south as Florida, the Bahamas, and Canary Islands. Another population lives in the Southern Hemisphere and has stranded in South Africa and Australia. The species does not inhabit the Southern Atlantic or Northern Indian Ocean, and appears to completely avoid tropical waters. No population estimates have been established, but it is believed to be the rarest species of whale.

Conservation

This species has not been hunted and has not been a victim of fishing nets.

References

*
*"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
* [http://www.int.iol.co.za/index.php?from=rss_News&set_id=1&click_id=79&art_id=nw20070709181848734C922798 Rare species found dead]

External links

* [http://www.amonline.net.au/factsheets/trues_beaked.htm Factsheets]
* [http://www.sci.tamucc.edu/tmmsn/29Species/MoreSpec/truesbeakedwhale.html Cetaceans of the World]
* [http://www.cms.int/reports/small_cetaceans/data/m_mirus/m_mirus.htm CMS]
* [http://www.wdcs.org Whale & Dolphin Conservation Society (WDCS)]


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