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True's Beaked Whale
Size comparison against an average human
Conservation status
Data deficient (IUCN)
Scientific classification
Phylum: Chordata Class: Mammalia Order: Cetacea Suborder: Odontoceti Family: Ziphidae Genus: Mesoplodon Species: M. mirus
Binomial name
Mesoplodon mirus True, 1913
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.

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.

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.

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.

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

Cetaceans Portal

• Cetacean Specialist Group (1996). Mesoplodon mirus. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 12 May 2006.
• 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
• Rare species found dead

• Factsheets
• Cetaceans of the World
• CMS
• Whale & Dolphin Conservation Society (WDCS)