Sperm Whale (Physeter macrocephalus)
Suborder: Odonticeti Family: Physeteridae
Common in Hawaiian waters.
Other known names:
Great sperm whale, Cachalot
General description and habits:
Sperm whales have an enormous square head which is up to a third of their overall body length. Males have larger heads in proportion to their bodies than females. They are covered in wrinkly prune-like skin and older males are sometimes badly scarred, especially around the head. Male sperm whales also have larger teeth and more of them than females. There are between 36 and 50 teeth in their long, narrow lower jaw. The upper jaw has tiny teeth that aren't needed and so they usually stay hidden behind the gums. The lower teeth are thick and conical, and can grow to 20cm long.
Like all toothed whales, sperm whales only have a single blowhole - on the left side near the front of the head. Baleen whales have two blowholes side by side. When they breathe out at the surface, their "blow" is low and bushy, and spouts forward and to the left. The sperm whale is the largest of all the toothed whales. Adult males reach 15 - 18 meters (49 - 60ft), adult females 11 - 12 meters (36 -40ft), and newborns are 3.5 - 4.5 meters (11.5 - 15ft). Adults can weigh up to 50 tonnes, ranging from 20-50. Newborns weigh about 1 tonne. Sperm whales spend most of their lives in either 'nursery schools' (adult females with male and female young) or 'bachelor schools' (males between about 7-27 years of age). Older males tend to live on their own or in very small groups and join nursery schools during the breeding season. Sperm whales breach and lobtail, and dive for long periods.
Identity Keys to use in the field:
Large square shaped head, Single blowhole, Blow/Spout goes forward and left, Short stubby flippers, Dark wrinkly skin, Dives for long periods, Low hump instead of dorsal fin, Bumps or "knuckles" from hump to fluke, Tail flukes lifted when diving, Tail flukes are triangular, Small eye.
Mainly squid but they will eat fish.
Sperm whales are found in most of the world's oceans, except the high Arctic. Big groups of them tend to be found in certain areas where the habitat is right for them. These would generally be areas where their favorite food is found, and where the temperature suits them. Sperm whales like deep water and so usually occur offshore; but they are sometimes found closer to land if water depth is more than 200 meters.
The current worldwide population of the sperm whale isn't known but we can be sure it is much smaller than it has been in the past. Around the mid-1940s, the sperm whale population was estimated to be about 2 million. At first the numbers stayed relatively high because whalers were targeting the larger baleen whales. However, by the 1960s their numbers had been drastically reduced as it became harder to find sufficient numbers of large baleen whales.
Hunting - Japan killed 5 out of a quota of 10 sperm whales it set itself in 2000 in the North West Pacific with another quota of 10 in 2001, Human disturbance, Chemical pollution, Entanglement in fishing nets
Sperm whales are world champion divers - they are thought to dive deeper than any other mammal in the world. Typically they dive to depths of 300-600 meters, but they can reach 2000 meters, and researchers think they may be able to go as deep as 3000 meters (nearly 2 miles) at a rate of up to 3 meters per second! It may be possible for them to spend up to 2 hours underwater without coming up for a breath. Sperm whales dive to hunt for giant squid that live very deep in the water. The whales each eat up to 1 tonne of squid every day. Some sperm whales have round scars all over their bodies that have been caused by the tentacles of giant squid. They also hold the record for the world's heaviest brain although their brains are only about 0.02% of their total body weight. Sperm whales use echolocation to hunt their prey, as it is too dark to see so far down in the ocean. In this way even blind whales are able to find food. The large square head of the sperm whale contains a cavity large enough for a car. It holds a yellowish wax known as spermaceti oil. Sailors used to carve pictures on sperm whale teeth. This art form is known as scrimshaw.