Blainville's Beaked Whale (Mesoplodon densirostris), or the Dense-beaked Whale, is the widest ranging mesoplodont whale and perhaps the most documented. The name "densirostris" is a Latinized form of "dense beak". Off the northeastern Bahamas, the animals are particularly well documented, and a photo identification project started sometime after 2002.

Physical description

The body of Blainville's Beaked Whale is robust, but also somewhat compressed laterally compared with other Mesoplodonts. The males have a highly distinctive appearance, the jaws overarch the rostrum, like a handful of other species, but does it towards the beginning of the mandible and then sloped down into a moderately long beak. Before the jaw sloped down, a forewords facing, barnacle infested tooth is present. One of the more remarkable features of the whale is the extremely dense bones in the rostrum, which have a higher density and mechanical stiffness than any other bone yet measured^[2]. At present, the function of these bones is unknown, as the surrounding fat and the brittleness of the bone make it unlikely to be used for fighting ^[2]. It has been suggested that it may play a role in echolocation or as ballast, but without sufficient behavioral observation, this cannot be confirmed^[2]. The melon of the whale is flat and hardly noticeable. Coloration is dark blue/gray on top and lighter gray on the bottom, and the head is normally brownish. Males have scars and cookie cutter shark bites typical of the genus. Males reach at least 4.4 meters (14 ft 6 in) and 800 kg (1800 pounds), whereas females reach at least 4.6 meters (15') and 1 tonne (2200 pounds). Juveniles are 1.9 meters long (6 ft 4 in) when born and weigh 60 kg (130 lb).

Population and distribution

This species of beaked whale is found in tropical and warm waters in all oceans, and has been known to range into very high latitudes. Strandings have occurred off Nova Scotia, Iceland, the British Isles, Japan, Rio Grande do Sul, South Africa, central Chile, Tasmania, and New Zealand. The most common observations take place off Hawaii, the Society Islands, and the Bahamas. The species does not migrate. It inhabits water 1600 to 3000 feet deep. Despite the relatively common nature of the whale, no population estimates are available.^[3]

Behavior

The whales are seen in groups of 3-7 individuals. Dives have been measured out to at least 22 minutes. When the cetacean surfaces, it does so slowly and with little splashing. It probably feeds mainly on squid as the stomach of one stranded individual contained only squid.^[4]

Conservation

The beaked whale has occasionally been hunted, but has never been a specific target. ^[3]

Specimens

• MNZ MM002350, collected Tongoia Beach, North of Napier, Hawke's Bay, New Zealand, 1998.

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
• Possible functions of the Ultradense bone in the rostrum of Blainville's beaked whale (Mesoplodon densirostris). Written by Colin D. MacLeod. Canadian Journal of Zoology, 80(1): 178-184 (2002). Available: here