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Sperm Whale

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Sperm whale calf close to surface
Perrine Doug/Perspectives/Getty Images

When you think of a whale, the sperm whale (Physeter macrocephalus) may come to mind, as this species most closely resembles most generic "whale" cartoons and drawings. The sperm whale is the largest odontocete, or toothed whale. This species is also iconic because the star of Herman Melville's book Moby Dick is a sperm whale.

Sperm whales are deep divers, capable of staying under water possibly up to 2 hours as they search for squid, their favorite prey.

The sperm whale's name has been shortened from 'spermaceti whale.' This name came from whalers, and was a reference to the milky substance in a whale's head that was thought to resemble semen. The milky substance in a sperm whale's head has nothing to do with reproduction, but is made by organs in the whale's head that produce sound.

These whales may be very social, depending upon their gender. Female and juvenile sperm whales may socialize and have stable social units of 7-12 animals, where the whales have been referred to as "constant companions". They may also have "casual acquaintances," in which social units temporarily seek out the companionship of whales in other social units. Adult males tend to roam among female social units when looking for mates, although they may also form "bachelor groups."

Description:

The scientific name of sperm whales has been debated over the years, as Linnaeus gave this whale two scientific names - Physeter catodon and Physeter macrocephalus. The latter is now more commonly used, and describes this whale well - "blower with a big head."

Sperm whales have large, blocky heads and stocky, wrinkled bodies with dark skin (not the pale skin that Moby Dick had, although albinism is possible in sperm whales). Instead of projecting upward, their spout points at a 45-degree angle and is located on the left front of a sperm whale's head, which is one way to recognize sperm whales at sea. Sperm whales display very noticeable sexual dimorphism in their size. Males reach about 60 feet in length and are about 3 times as long as females. Males can reach weights up to about 125,000 pounds, and females weigh about half as much.

Sperm whales have 17-30 pairs of teeth. These are located only on their lower jaw, and these teeth fit into sockets in the upper jaw when the whale closes its mouth.

A sperm whale produces a substance called ambergris in their lower intestine. This substance is thought to protect the whale from sharp objects such as squid beaks before they are expelled. Ambergris was sought by whalers and has been (and still is) used to make perfume.

Classification:

  • Kingdom: Animalia
  • Phylum: Chordata
  • Subphylum: Vertebrata
  • Superclass: Gnathostoma
  • Superclass: Tetrapoda
  • Class: Mammalia
  • Subclass: Theria
  • Order: Cetartiodactyla
  • Suborder: Cetancodonta
  • Infraorder: Cetacea
  • Superfamily: Odontoceti
  • Family: Physeteridae
  • Genus: Physeter
  • Species: macrocephalus

Feeding:

Sperm whales feed on squid. While they are famous for feeding on giant squid, which can reach weights over 200 pounds, the squid that sperm whales prey on may also be as small as .2 pounds. They may also eat fish. It is estimated that a sperm whale eats 3-3.5% of their body weight each day. For a sperm whale weighting 40 tons (80,000 pounds), that would be about 2,400 pounds of fish per day.

Reproduction:

Sperm whales become sexually mature when they are in their early teens, but may not actively take part in mating until they are around 20 years old. The female's gestation period is 15-18 months, after which she gives birth to a calf that is about 11-16 feet long and 2,000 pounds when born. The calves nurse for 2-4 years. During this time, the calf does not undertake deep dives, but is watched over by other sperm whales at the surface while its mother is on deep feeding dives. Female calves remain in their mother's social unit, while males leave the unit when they are about 6-12 years old. The lifespan of sperm whales is thought to be around 70 years.

Habitat and Distribution:

Sperm whales live around the world in waters from the Arctic to Antarctica. Females tend to live in tropical and subtropical waters, while males may travel to colder waters.

Communication and Vocalizations:

In addition to the social units described above, there are "vocal clans" of sperm whales, with thousands of sperm whales within the clan having a distinct dialect. These whales also appear to have similar movements, habitats, diet and reproductive success.

Sperm whale sounds include 'clicks,' which are produced by feeding whales and used in echolocation and 'codas,' which are sequences of clicks produced when socializing and at the beginning and end of foraging dives.

Conservation:

Sperm whales may be preyed-upon by orcas and sharks.

According to NOAA, about 1,000,000 sperm whales have been taken by whalers over the past 200 years. Currently, these whales are protected by the Endangered Species Act and Marine Mammal Protection Act in the U.S. and there are thought to be anywhere from 200,000 to 1,500,000 sperm whales worldwide.

Current threats include ocean noise, ship strikes, entanglement, and pollution.

The sperm whale is classified as vulnerable on the IUCN Red List.

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