Every animal, whether it's a small flying insect or the large whale, is characterized by specific attributes that help in their identification. With respect to the sperm whale, it's the large head with nearly rounded forehead that make it easily recognizable to us. It is the largest member of the family of toothed whales, which also has dolphins and beaked whales to its credit. At 9 kg, its massive brain is recorded to be the largest for any animal on the planet.
Sperm Whale: The Largest Toothed Predator
The sperm whale is a mammal with a dark gray skin. It is categorized as a toothed whale, as it bears teeth instead of baleens. The name is assigned with respect to the oily, milky-white fluid that fills up the head of the species. This substance is called spermaceti, and was once believed to be its sperm. Till date, marine biologists are not sure about the actual role of spermaceti. As for the closest guess, it is believed that this waxy matter helps the sperm whale in buoyancy regulation at the time of diving deep into the sea.
Adult male sperm whales (bulls) can grow to a length of 20 meters or more, with the head portion occupying one-third of their total body length. The average body weight of this enormous mammal is 57,000 kg. Pygmy sperm whale is a rare species; smaller in size (at 3 - 4 meters) and weighing about 408 kg. The smallest species is the dwarf sperm whale, measuring about 2.7 meters in length and weighing not more than 250 kg.
The lower teeth of sperm whale are cone-shaped and weigh about 1 kg. In both sides of the lower jaw, the number of teeth is more than 20. The upper jaw bears only rudimentary teeth. When it closes its mouth, its lower jaw properly fits into its upper jaw. The teeth are also used for defense mechanism during fights between bulls.
This enormous mammal has ability to swim very deep in the sea and rise up again. It is claimed that this whale can dive to about 9,800 meters deep, while holding its breath for 1½ hours. It holds the title for the deepest diver of all mammals. Dwarf sperm whale is actually a deep diver that prefers to feed in coastlines.
Its ability to make vocal sounds (or clangs) for the purpose of echolocation and communication is unique. In fact, they produce the loudest sound of all the animals in the sea. With the help echolocation, these whales can predict the size, shape, and distance of their prey.
Sperm whale is a true carnivore, which primarily feeds on squids (both, colossal and giant squids) that inhabit the bottom of the sea. Other preferred food items include octopi, skates, and other marine species. On an average, adult whales consume more than 900 kg of squid and fish per day.
Male sperm whales attain sexual maturity at the age of 18 years, while female attain it at 7 - 13 years. After mating, the female undergoes a gestation period of 14 - 16 months and gives birth to a single calf. The young suckles from its mother and other females in the group for about 42 months. Interestingly, the lactation period in this species can be as long as 13 years at times.
The female sperm whale along with their calves dive together in groups. Such groups are called pods, each of which comprise about 15 - 20 whales. In contrast, the males are often spotted alone in higher latitudes, or they keep on migrating from one group to another.
Whaling of the sperm whales is done for ambergris, which is a gray, waxy substance secreted by their stomach. Freshly isolated ambergris has an unpleasant smell (similar to that of feces), but the fragrance becomes sweet after some time, and is widely used in perfume industry.
Uses of Spermaceti
Spermaceti protects the stomach lining from being bitten by squids. Very often, the sperm whale regurgitates it in large amounts. The spermaceti extracted from the head of sperm whale solidifies when it is exposed to low temperature condition. Commercially, it is used in making machine oils, candles, soaps, and other cosmetic products.
Other than humans, sperm whales are threatened by very few natural predators; the killer whale (orcas) being one of them. Unfortunately, their population has declined significantly due to large-scale whaling. Also, pygmy and dwarf sperm whales are rare species. In their natural habitat, the lifespan of a sperm whale is about 70 years.