Whales

Andrews’ Beaked Whale - Mesoplodon bowdoini

This whale, named Andrews’ Beaked Whale was first described in 1908 by R C Andrews and subsequently named after George Bowdoin, a trustee of the American Museum of Natural History. Most of the information gained on this whale, has been from some 35 strandings of this animal. While cranial anatomy and tooth morphology is used, the distinguishing features may apply only to adults. Therefore the identification of females and young whales can be particularly problematic.

Andrews' Beaked Whales are found in temperate waters of the Southern Hemisphere. Most records are from strandings in New Zealand, Australia and sub-antarctic Macquarie and Campbell Islands. As it is seen so rarely, it is possible that this species may live in deep water, far from land.

Adults may grow to a length of 4.9 meters and weigh approximately 1 to 1.5 tonnes. Their length at birth is 2.2 meters. The melon is not prominent, their beak is short and thick with their lower jaw having a distinctive upward arch which is more prominent in males than females. It has a narrow head and a deep, round body at mid-length. It is predominantly dark blue-black in colour, with the tip of the beak, as far as the posterior edge of the teeth, which is white. However, females usually have less white on their beaks. The ventral side of the flanks is also pale, with adult males sometimes having a greyish 'saddle' from behind the blowhole to the dorsal fin. Males are often covered with many long, linear tooth-rake scars which are probably from infliction by other males. . Adult males have a large pair of teeth which curve outwards slightly to lie outside the upper jaw. They are wide and flat, with a curved posterior edge and a denticle at the tip which points forward. Their erupted teeth are covered by skin and gum tissue, therefore only the tip of each tooth is exposed. As with most other beaked whales, the teeth do not erupt in females.

As the diet of this whale species is unknown, it is presumed to feed on deepwater squid and fish, possibly crustaceans and echinoderms that are found on the sea flood. They presumably capture their prey by suction, as they lack function teeth.

These whales are rarely seen at sea possibly due to their deep ocean distribution, elusive behaviour and low numbers, therefore not much is known about them, their breeding in particular. It appears their calving season in New Zealand waters is during summer and autumn.

The Andrews’ Beaked Whale is at times confused with the Blainville’s Beaked Whale. The differences are that the jawline of the Blainville’s Beaked Whale is much more highly arched than that of the Andrews’ Beaked Whale. Also the Andrews’ Beaked Whale has a proportionally longer beak. The Ginkgo-toothed Beaked Whales are difficult to distinguish from the Andrews’ Beaked Whale at sea.