True's beaked whale - Mesoplodon mirus

Taxonomy & Nomenclature

Scientific Name Mesoplodon mirus
Author True, 1913
Taxonomic Rank Species
Taxonomic # 180508
Common Names English: True's Beaked Whale
Current Standing valid
Taxonomic Parents Kingdom: Animalia
  Phylum: Chordata
    Subphylum: Vertebrata
      Class: Mammalia
        Subclass: Theria
          Infraclass: Eutheria
            Order: Cetacea
              Suborder: Odontoceti
                Family: Hyperoodontidae
                  Genus: Mesoplodon
Taxonomic Children
Synonyms (since 1950)

Taxonomic data is courtesy of the Integrated Taxonomic Information System (ITIS)
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Physical Description / Field Identification

In morphology and coloration, True’s beaked whales are not known to differ substantially from other mesoplodonts, although they have a slightly bulging forehead and prominent beak.

These beaked whales are characterized by the position of the mandibular teeth at the very tip of the lower jaw. The teeth are oval in cross-section, lean forward, and are visible outside the closed mouth of adult males.

Both sexes are known to reach lengths of slightly over 5 m. Newborns are probably between 2 and 2.5 m. Weights of up to 1400 kg have been recorded.

Can be Confused With

At sea, True’s beaked whales are difficult to distinguish from other mesoplodonts. The only other species in which males have oval teeth at the tip of the lower jaw is Longman's beaked whale. However, the latter species is generally much larger and the forehead is more steeply-rising than in True’s beaked whale.


True’s beaked whales are known only from strandings in Great Britain, from Florida, United States to Nova Scotia, Canada in the North Atlantic, and from southeast Africa in the Indian Ocean.

Ecology and Behavior

There is almost no information available on the natural history of this species of beaked whale.

Feeding and Prey

Stranded animals have had squid (Loligo sp.) in their stomachs.

Threats and Status

Almost no information is available on the threats and status of this species; True’s beaked whales are currently ‘Data Deficient’ (IUCN) and ‘Not Listed’ (ESA).



Dalebout, M. L. 2002. Species identity, genetic diversity, and molecular systematic relationships among the Ziphiidae (beaked whales). Ph.D. dissertation, University of Auckland, New Zealand.

Houston, J. 1990. Status of True’s beaked whale, Mesoplodon mirus, in Canada. Canadian Field-Naturalist 104:135-137.

Mead, J.G. 1989. Beaked whales of the genus Mesoplodon. pp. 349-430 in S.H. Ridgway and R. Harrison, eds. Handbook of marine mammals, Vol. 4: River dolphins and the larger toothed whales. Academic Press.

Pitman, R.L. 2002. Mesoplodont whales Mesoplodon spp. pp. 738-742 in W.F. Perrin, B. Würsig and J.G.M. Thewissen, eds. Encyclopedia of marine mammals. Academic Press.

ITIS TSN180508
Status - ESA, U.S. FWS
Status - Red List, IUCN
    DD (Europe)
    LC (Global)
#records (spatial)38
#records (non-spatial)0
Year1917 - 2022
Latitude-37.15 - 53.70
Longitude-75.88 - 22.17
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