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Ziphiidae:
A beaked whale is any of at least 20 species of small whale in the family Ziphiidae. They are one of the least-known families of large mammals: several species have only been described in the last two decades, and it is entirely possible that more remain as yet undiscovered. Six genera have been identified. Three of these, Indopacetus, the Hyperoodon and the Mesoplodon, are united in a single subfamily, the Hyperodontinae. They possess a unique feeding mechanism known as suction feeding. Instead of catching their prey with teeth, it is sucked into their oral cavity. Their tongue can move very freely, and when suddenly retracted at the same time as the gular floor is distended, the pressure immediately drops within their mouth and the prey is sucked in with the water. The known beaked whales range in size from about 3.4 metres to almost 13 metres, and can weigh anywhere between 1 and 15 tons. They are found in all oceans and most species rarely venture into the relatively shallow water of the continental shelves. They are very difficult to identify in the wild: body form varies little from one species to another, and the observer must rely on often subtle differences in size, colour, shape of forehead, and length of beak. |
