Taxonomy & Nomenclature
Physical Description / Field Identification
Although the body shape of this whale is not very distinctive, the teeth of adult males are unique. The long tusks emerge from near the middle of the lower jaw and curl backward and inward, extending over the upper jaw, often preventing it from opening more than a few centimeters. How the animals eat with such an arrangement is unknown.
The complex color pattern is better-known than that of most mesoplodonts, as this species is known from more specimens than any other in the genus. The body is mostly gray or black, sometimes with a purple or brown tinge. Much of the underside is white around the urogenital opening, between the flippers, on the beak, and in a band of variable width around the head. Variable white or light gray patches tend to be found on the back and sides.
Adult females reach lengths of at least 6.2 m and males reach 5.9 m, making this the largest of the mesoplodonts. Length at birth is unknown, but is probably close to 3 m.
Can be Confused With
The unique tusks of adult males of this species will make them identifiable, if seen. Females and subadults will likely be impossible to distinguish from other mesoplodonts.
Distribution
Strap-toothed beaked whales may have a continuous distribution in cold temperate waters of the Southern Hemisphere; there have been strandings in South Africa, Australia, Tasmania, New Zealand, Tierra del Fuego, Uruguay, and the Falkland Islands. The seasonality of strandings suggests that this species may migrate.
Ecology and Behavior
Groups of up to three individuals have been seen. These animals are difficult to approach. Strap-toothed whales are commonly stranded, but little has been learned from the few sightings of live animals. Calving appears to occur in spring to summer.
Feeding and Prey
They eat squid, and the single stomach examined also contained a piece of algae.
Threats and Status
There is little information available on the status of the strap-toothed whale. Currently, this species is ‘Data Deficient’ (IUCN) and ‘Not Listed’ (ESA).
Links
References
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.
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.
