Whales

Cuvier’s Beaked Whale - Ziphius cavirostris

The Cuvier’s Beaked Whale is also called the Goose-beaked Whale, as its head is said to be shaped like the beak of a goose. This animal was named after George Cuvier after finding part of a skull in France in 1804. These species can grow up to about seven metres in length and weighing 2-3 metric tonnes. They live for approximately forty years.

It has a short, white or creamy coloured slightly bulbous beak in comparison with other species in the family. A white strip runs to the dorsal find about two-thirds of the way down its back. Their bodies varies from colour to colour with each individual, some being dark grey, with others being a reddish-brown. Their backs are usually darker than their bellies, but some have reverse coloration. Younger whales are usually lighter in colour than the adults. Their heads are almost always white, especially in the older males. Adult males have two large teeth on the lower jaw that grow up to 8 centimeters. But in females, the teeth never break through the gums. Some animals have been found with 15-40 teeth that have never broken through. They have small rounded flippers that fold into ‘flipper pockets’ on their flanks and relatively tall fins.

There does not seem to be a specific breeding season for the Cuvier’s Beaked Whale, therefore little is known about their reproduction. Males are known to fight for their dominance of access to females using their two small teeth on their lower jaws. Gestation is about twelve months and the young are born late summer to early autumn. Males become sexually mature when they reach about 5.5 metres and females when they reach 6. The sex ratio is thought to be 67 % males to 33 % females.

Single males are occasionally spotted, but these species usually travel in pods of around 15. Their rounded heads are sometimes seen during their blow and they breathe at the surface for about 20 seconds before their next dive. They are known to be deep divers and plunge vertically for about 30 minutes or longer. Their diet consists mainly of squid, deep water fish, crabs and starfish. Their blow is low and inconspicuous. It is most often seen when the animal returns to the surface after a long dive which may last for up to 40 minutes. Before deep dive they typically arch their back steeply and sometimes raise their tail. Breaching has only been observed very occasionally.

One of the threats to the Cuvier’s beaked whale is still the hunting being carried out in Japan and South America for meat for human consumption and for bait for crab fisheries. They are also caught in fishing nets and lines. Since their major prey is squid they will swallow things which resemble a swimming squid, such as plastic bags. These are known to get stuck in their gut and eventually cause their death. They are highly sensitive to noise which is why a higher number of strandings have been recorded in noisy seas such as the Mediterranean. A relatively small number of 20 individuals have been killed by whalers each year.