Sperm Whales are the largest of the toothed whales and the largest living carnivore. The sperm whale is easily recognized by it’s massive head and prominent rounded forehead. They have the largest brain of any creature known and their heads hold a large quantity of spermaceti (milky white waxy substance in the head cavity). During the days of commercial whaling, sperm whales were so named because when the head was cut open it was found to contain a milky white substance and the whalers once believed that the fluid was sperm. Spermaceti is a high quality oil and was used originally in lamp oil and later as an industrial lubricant, in cosmetics, automatic transmissions, and pharmaceutical compounds, making this species highly valuable to whalers.
Scientists still do not fully understand the function of spermaceti. One common theory is that fluid, which hardens to wax when cold, helps the whale alter its buoyancy so it can dive deep and rise again. Sperm whales are known to dive as deep as 3,280 ft in search of squid to eat, which means these whales must hold their breath for up to 90 mins on such dives.
Sperm Whales have 20-26 pairs of cone shaped teeth in their narrow lower jaw. Each tooth is 10-20 m long and can weigh as much as one kilogram. However, the existence of teeth in sperm whales is a bit of mystery as the teeth are not considered to be necessary for feeding on their primary food item, giant squid. Some sperm whales have scars on their bodies caused by giant squid tentacles during fights. Although sperm whales are known to eat a wide variety of sea creatures their primary prey items are deep-water squid which they are believed to catch by the suction method of eating.While sperm whales can dive to depths of up to 1 km to locate the rarely seen squid, most dives are to approximately 400 m and last for 35 mins to 1 hour. After a long dive, sperm whales remain at the surface for around 8 mins – it is during this time that sperm whales were most susceptible to whalers.
Sperm whales can be quite gregarious and known to breach, spyhop (vertically pokes it head out of the water) and lobtail (sticking their fluke out of the water into the air, swing it around, then slap it on the waters surface). A sperm whale spends most of its life in either nursery schools (adult females with young) or bachelor schools (males between 7 & 27 years of age) although older males tend to live on their own in very small groups and join nursery schools during breeding season. The only natural predator of the sperm whale is the orca and even then most attacks are not thought to be fatal. During such attacks however, the females show defensive behaviour of calves by creating a ring with the calves in the centre, called a marguerite. These rings may have their heads or tails on the outside.
Sperm whale adult males grow to be about 50-60 feet long, weighing about 40-50 tons, whereas females are smaller about 33-40 feet long, weighing 14-18 tons. The four chambered heart of the average sperm whale weighs about 277 pounds! Sperm whales have flipper that are about 5 feet long and 3 feet wide, they do not have a dorsal fin but there is a small hump two-thirds of the way down its back. There are also ridges between the hump and the tail flukes.
Sperm whales are found in most of the world’s oceans, except the high Arctic and prefer deep water. They can be found in large numbers where food is abundant, and where the sea temperature suits them.
The species has been drastically affected by commercial whaling in the past and numbers are thought to have been decimated. Sperm whales are still threatened by hunting, principally by Japan. The current worldwide population is not known and the conservation status of the sperm is listed as Vulnerable.
Video: Friendly Sperm Whale