Whales - Species | Arnouxs Beaked Whale

Arnoux's Beaked Whale - Berardius arnuxii

The Arnoux's beaked whale was named after the French commander of the vessel that carried the first specimen from New Zealand to France in 1876. It is a rare species and is often called the southern four-toothed whale because the lower jaw is longer than the upper and the four teeth found in the lower jaw are even visible when the mouth is closed. They are known to have many similarities to the Baird’s Beaked Whale, except for that the Arnoux’s whale is generally shorter. Estimated lengths have been approximately 12 meters, with the Baird’s Beaked Whale being 12 – 13 meters. They are deep sea whales that feed on deep sea fish, squid and occasionally crustaceans. They are found mainly in the southern Pacific in south eastern Australia, northern New Zealand and the southern Atlantic and Indian Ocean. They are generally found in smaller groups of 6 – 10 but sightings of larger groups of approximately 80 individual whales have been reported. Strandings have been predominantly found around New Zealand.

The Arnoux’s Beaked Whales have a very long prominent beak with a bulbous melon found at the centre of the forehead. This melon is an oily, fatty lump of tissue, but its function is not quite understood by scientists. Their body shape is slender, its body is uniformly coloured and the flippers are small and rounded. Their dorsal fin is similarly small and rounded and set about three-quarters of the way along the back. Both species pick up white scars all over the body as they age and, in time, this becomes a rough indicator of their age. These whales are mostly dark brown in colour with a paler colour on the head and ventral side, which also sometimes has white patches.

Arnoux’s Beaked Whales have been seen to be swimming under sea up to 7 kilometers deep between breaths. They were observed to have changed direction before diving between 249-366 meters for long periods of time during breathing intervals near the surface in extremely cold water. The whales were apparently able to find other breathing sites in what appeared to be unbroken ice. The water surface temperature in the area was studied to be -0.8°Celcius but unfortunately, some of these whales have been known to become trapped under the ice despite being such good swimmers. They have been known to enter packed ice and are thought to live close to the ice edge in summer and farther out in open water during winter.

This whale species seems well adapted to life in ice-covered waters and may be able to exploit food resources inaccessible to other whales or predators in the region. The presence of bottom-living prey species and small stones found in the stomachs of these whales suggests that they are capable of diving to the seabed in water depths of 1,000 meters or more. They are thought to capture prey by means of suction feeding, using their piston-like tongues and expandable throat-grooves to suck prey into the mouth.

Not much is known about the life history of Arnoux's Beaked Whale. They are usually very shy creatures and capable of diving for an hour or more, hence being difficult to observe and positively identify. They have never been exploited and although no abundant estimations are available, the population is not believed to be endangered.