Splay-toothed Beaked Whale

Andrews' beaked whale is a medium-sized beaked whale, with males typically reaching lengths of 3.4 m (11.2 ft) to 4.4 m (14.4 ft) and females 3.7 m (12.1 ft) to 4.9 m (16.1 ft). Calves are around 2.2 m (7.2 ft). Weight is uncomfirmed, however mesoplodonts of similar sizes are recorded at 1-1.5 t. It has a robust, spindle-shaped body, low melon, and short, thick beak with a pair of large, flattened tusks that only erupt from the arched lower jaw in adult males. The teeth of females remain unerupted in the less-arched jawline.

Adult males are dark brown or black with a contrasting pale lower jaw and rostrum tip, while females are bluish-gray to slate grey in the dorsal surface, fading to pale sides and underside and also share the pale to whitish lower jaw and rostrum tip. Both sexes may have a small, light or pale patch in front of the eye. Subadult males look very similar to females, especially before their tusks develop. Calves are dark dorsally and light ventrally with a notably dark eye patch.The flippers are small and narrow and are set relatively low on the body. Slight depressions known as "flipper pockets" are located behind the flippers and allow the whales to better streamline themselves while diving. The dorsal fin is small, triangular and positioned far back on the body. The flukes are broad relative to the body and typically lack a prominent median notch.

Andrews' beaked whales live in the Southern Hemisphere, and the precise range is uncertain. Some 48 stranded specimens have been recorded in Australia and New Zealand, Macquarie Island, the Falkland Islands, and Tristan da Cunha. That range may imply a circumpolar distribution. However, there are no confirmed sightings to confirm this.

Like other Mesoplodon species, Andrews' beaked whales may form pods of 1-5 individuals. Males are notable in having extensive, linear pale to white scarring throughout the body which contrasts against the dark skin. These are presumed to be the result of use of tusks in male-male combat, perhaps for access to females. The calving season may be during summer and autumn off New Zealand. Otherwise, any behavior is completely unknown.

Andrews' beaked whales are likely deep-diving, echolocating suction-feeders. Like other beaked whales, this species possess a pair of V-shaped throat grooves that are thought to facilitate suction feeding by creating negative pressure within the mouth as the tongue retracts and the throat grooves expand, powerfully drawing prey inward like a biological vacuum. While the exact diet of this species is unknown, it likely preys on deep-sea squid such as Histioteuthis, Taonius pavo, and Chiroteuthis, as well as fish.