Arnoux'S Beaked Whale

Arnoux's and Baird's beaked whales, have very similar features and would be indistinguishable at sea if they did not exist in disjoint locations. Both whales reach similar sizes, have bulbous melons, and long prominent beaks. Their lower jaw is longer than the upper, and once sexual maturity is reached the front teeth are visible even when the mouth is fully closed. The Baird's and Arnoux's beaked whales are the only whales in the Ziphiidae family where both sexes have erupted teeth. The teeth in the Ziphiidae are presumed to be used by males for fighting and competition for females. Ziphiidae have the most prevalent and pronounced markings caused by teeth scarring among the cetaceans. Front-facing teeth may be covered in barnacles after many years.

Arnoux's beaked whales inhabit great tracts of the Southern Ocean. Beachings in New Zealand and Argentina indicate the whale may be relatively common in the Southern Ocean between those countries and Antarctica; sporadic sightings have been recorded in polar waters, such as in McMurdo Sound. It has also been spotted close to South Georgia and South Africa, indicating a likely circumpolar distribution. The northernmost stranding was at 34 degrees south, indicating the whales inhabit cool and temperate, as well as polar, waters. There is no stock report for the Arnoux's beaked whale to date by NOAA.

Killer whales are the only animal that could be a potential predator. Some scarring from attacks is evidently caused by them, notably on their flukes, dorsal and pectoral fins. White, circular or oval-shaped wounds are often present and are caused by cookiecutter sharks taking chunks of tissue from their bodies.

Arnoux's beaked whales are 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.

Prey taxa include Batoteuthis skolops, Moroteuthopsis longimana, Galiteuthis glacialis and Taonius sp. and some fish.

Arnoux's beaked whale has rarely been exploited, and although no abundance estimates are available, the population is not believed to be endangered.

Arnoux's beaked whale is covered by the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MOU).