SPERM WHALES: Physeteridae

PHYSICAL CHARACTERISTICS

The family of sperm whales contains the largest toothed whale—the giant sperm whale—and two smaller toothed whales. All are dark gray above, lighter gray on the belly, and have erupted (visible) teeth only in the lower jaw. Although these animals range in size and weight from 9 feet (2.7 meters) and 600 pounds (270 kilograms), to 60 feet (18.3 meters) and 125,000 pounds (57,000 kilograms), they have other physical features in common.

All members of this family have a spermaceti (spur-mah-CEE-tee) organ in their forehead. This produces a waxy substance called spermaceti. At the animal's body temperature, it is a clear yellowish liquid. After processing, it becomes a white waxy solid. It was prized in the 1800s and 1900s for making smoke-free candles and soap and as a way to waterproof cloth (called oilskins). Later it was used in cosmetics, ointments, as a lubricant for watches and machinery, and in automatic transmission fluid. Today it has been replaced by human-made oils and waxes.

The purpose of the spermaceti organ is not clear. Some scientists think that it helps the whale regulate its buoyancy, or ability to sink or float, during dives. Others believe that it is used to focus the sounds made for echolocation (eck-oh-loh-KAY-shun) and communication. Echolocation involves making sounds that bounce off objects. Sense organs pick up the echo or reflected sound and use information about the timing, direction, and strength to determine the location of objects. Echolocation allows whales to find food in water so deep that there is no natural sunlight.

Members of the sperm whale family share other physical characteristics. Their heads are asymmetrical, meaning that if they were divided in half along the long axis of the body, the features in the right half would look different from the features in the left half. This is not common in mammals. As a result, a single S-shaped blowhole that allows the whale to breathe is located on the left side of the body. The left nasal passage is used for breathing, but the right one is narrower and is thought to be used to produce sounds.

GEOGRAPHIC RANGE

Members of this family are found in oceans worldwide.

HABITAT

These are deep-water whales, living in water over 3,300 feet (1,000 meters) deep. Smaller species may live in slightly shallower water.

DIET

Sperm whales eat mainly squid, although they will also eat fish, crabs, and octopus that live on or near the ocean bottom.

BEHAVIOR AND REPRODUCTION

Sperm whales appear to be very social, communicating through a series of clicks, whistles, and similar sounds. It appears as if each whale has a personal identification sound called a coda, that it makes when it meets other whales. These animals live in small groups. The composition of the group with regard to age, gender, and size changes as these animals age.

WHAT IS SPERMACETI?

Spermaceti or sperm oil is a waxy substance, not a true oil, found in the head of marine mammals, especially the giant sperm whale. At the animal's body temperature, it is a clear yellowish liquid. After processing, it becomes a waxy solid. It was prized in the 1800s for making candles and soap and as a way to waterproof clothing (called oilskins). It was later used in cosmetics, ointments, and as a lubricant for watches. Today man-made oils and waxes are used in its place. An average sperm whale has 1,900 liters (500 gallons) of spermaceti.

Almost nothing is known about reproduction in the smaller species of this family. Female giant sperm whales give birth about every five years after a pregnancy that lasts between fourteen and sixteen months. Mothers and calves have strong social bonds, and calves nurse for many years after birth.

SPERM WHALES AND PEOPLE

Sperm whales were hunted for their spermaceti, blubber, and meat for many years. Minimal hunting still occurs. In parts of New Zealand, sperm whales form the basis of whale watching ecotoursism, where tourists observe whales without disturbing them.

WHAT IS AMBERGRIS?

Ambergris is a substance made in the digestive system of sperm whales. Sperm whales eat squid, which have sharp beaks that they use for biting food. The whales cannot digest the beaks of the squid, and eventually they begin to irritate the whale's digestive system. In response, sperm whales produce a material to cover the beaks. This is known as ambergris. It is rare and valuable. Since ancient times, ambergris has been used in perfumes to make the scent remain longer. Today human-made additives are available that do the same thing.

CONSERVATION STATUS

Not enough is known about the smaller sperm whales to give them a conservation rating. Although there is some debate about population size, giant sperm whales are considered Vulnerable, facing a high risk of extinction, because of slow recovery from population declines that resulted from hunting.

SPERM WHALE (Physeter macrocephalus): SPECIES ACCOUNTS

Physical characteristics: Sperm whales, sometimes called giant sperm whales to distinguish them from the smaller members of this family, are the largest toothed whales. They can reach 60 feet (18.3 meters) in length and weigh 125,000 pounds (57,000 kilograms). Males are much larger than females, who reach only about 36 feet (11 meters) and 33,000 pounds (15,000 kilograms). Although these whales are usually dark gray, they can also be black or white (albino). An albino sperm whale is famous as the monster great white whale in Herman Melville's story Moby Dick.

Sperm whales, especially males, have huge square asymmetrical heads that take up about one-third the length of their body. They have the largest brain of any mammal, larger even than the brain of the giant blue whale, the largest mammal on earth. Their brain weighs an average of 20 pounds (9.2 kg). For comparison, the average adult human brain weighs less than 3 pounds (1.3 kilograms). The spermaceti organ can contain more than 500 gallons (1,900 liters) of spermaceti

oil. Their blubber can be almost 14 inches (35 centimeters) thick. Sperm whales have about thirty-five to fifty large cone-shaped teeth in their lower jaw only. When the whale closes its mouth, these teeth fit into pockets in the roof of the mouth. These teeth were prized by sailors who carved pictures on them in an art form known as scrimshaw.

Geographic range: Giant sperm whales are found in every ocean of the world.

Habitat: These whales live in deep water and are often found near underwater features such as seamounts (underwater mountains that do not rise above the surface of the ocean) and sharp drop-offs.

Diet: Sperm whales hunt their prey by echolocation deep in the ocean where there is no sunlight. They mainly eat squid, including the giant squid that can be over 50 feet (15 meters) long. Many whales have scars on the head made by the suckers of these squid as they battle the whale. They also eat smaller squid, fish, and sharks.

Behavior and reproduction: Giant sperm whales are champion divers and are able to dive deeper than any other whale. They can dive to depths of more than a mile (2.2 kilometers), and stay under water for an hour. Some scientists believe that they may be able to dive to depths of 10,000 feet (3,000 meters). More typically, these whales dive to depths of 1,000 to 2,600 feet (300-800 meters) and remain under water for thirty to forty-five minutes. They then rest at the surface for about ten minutes before diving again. Females do not dive as deep as males and may spend more time at the surface with their calves. These whales swim at about 6 miles per hour (10 kilometers per hour) but can reach speeds of 19 miles per hour (30 kilometers per hour) when hunting or avoiding danger.

Females become sexually mature and able to reproduce when they are about eight years old. Males may be capable of reproducing earlier, but usually do not do so until they are nineteen or twenty years old. Females give birth every five to seven years. The mother-calf bond is strong and socially important. Mothers may continue to nurse their young for up to thirteen years. Mothers and calves form groups of about twenty to forty individuals (although one group of 3,000 to 4,000 animals was seen off the coast of South America) that appear to stay together and assist each other. For example, since calves cannot make deep dives, some females will take turns staying at the surface guarding the young from killer whales while their others dive for food.

As the young mature, the males leave the group and swim with other young males in groups of about twelve to fifteen individuals. As they grow older, they split off into smaller and smaller groups. It is common for an old male to swim alone. Males tend to move toward the poles and come back to warmer water where the female groups stay when it is time to breed. The males fight for the right to breed, which is why young males rarely start reproducing until age twenty. Once mating has occurred, the males leave the group of females and calves and go off on their own again. Sperm whales are thought to live about seventy years.

Sperm whales make a wide variety of sounds with the help of specially modified nasal passages and air sacs. The sounds they make are loud and carry well over long distances. It appears that each whale has a signature "song" to identify it to other whales. They also make clicks for echolocation and ringing sounds that may be involved in attracting a mate.

Sperm whales and people: Sperm whales have been hunted since the early 1700s, with peak whaling activity between 1880 and 1930 and 1950 to 1975. They are valued for their spermaceti, oil, and ambergris (AM-bur-gris), a waste product used in manufacturing perfumes. Whale meat is also eaten in some countries such as Japan.

Conservation status: Sperm whale hunting stopped in 1985. However, in 2000, Japan resumed hunting for what they called "scientific research" and has continued to kill between five and ten sperm whales each year. Sperm whales are considered Vulnerable. Because it takes them so long to mature and they have calves only every five to seven years, it will take a long time for their populations to recover from hunting. They are also at risk from collisions with ships and accidental entanglement in fishing nets and transatlantic communication cables. ∎

PYGMY SPERM WHALE (Kogia breviceps): SPECIES ACCOUNTS

Physical characteristics: The pygmy sperm whale is one of two small species in this family. These whales are about 11 feet long (3.4 meters) and weigh about 600 pounds (400 kilograms). They have blue-gray backs and a shape that makes them look something like a shark. Unlike the giant sperm whale, their head is only about 15 percent of their body length. They also have a much smaller spermaceti organ, and their blowhole is located on the left side of the forehead. Pygmy sperm whales have about thirty sharp, curved teeth only in the lower jaw.

Geographic range: These whales are found worldwide in temperate and tropical water.

Habitat: Pygmy sperm whales live in deep ocean and less deep water over continental shelves. They prefer moderate or warm waters and avoid the very cold waters of the Arctic.

Diet: Pygmy sperm whales feed on squid, octopus, fish, and crabs. They eat deep-dwelling species as well as species that live in the less deep waters over continental shelves.

Behavior and reproduction: Little is known about these animals. They have been seen floating without moving on the surface or swimming slowly. They are not often observed, but when they are seen, they are often in mother-calf pairs or in groups of fewer than five animals. These animals appear to give birth to a single calf every year after a pregnancy lasting eleven months. Beyond that, little is known about their mating behavior.

Pygmy sperm whales and people: These animals are rarely seen. Occasionally they are accidentally caught in fishing gear.

Conservation status: Too little is known about the population of pygmy sperm whales to give them a conservation rating. ∎

FOR MORE INFORMATION

Books:

American Cetacean Society, Chuck Flaherty, and David G. Gordon. Field Guide to the Orcas. Seattle: Sasquatch Books, 1990.

Carwadine, Mark, and Martin Camm. Smithsonian Handbooks: Whales Dolphins and Porpoises. New York: DK Publishing, 2002.

Mead, James G., and Joy P. Gold. Whales and Dolphins in Question: The Smithsonian Answer Book. Washington, DC: Smithsonian Institution Press, 2002.

Nowak, Ronald. M.Walker's Mammals of the World Online 5.1. Baltimore: Johns Hopkins University Press, 1997. http://www.press.jhu.edu/books/walkers_mammals_of_the_world (accessed on July 8, 2004).

Web sites:

American Cetacean Society. http://www.acsonline.org (accessed on July 8, 2004).

Bird, Jonathan. "Sperm Whales: The Deep Divers of the Ocean." Oceanic Research Group. http://www.oceanicresearch.org/spermwhales.htm (accessed on July 8, 2004).

Culik, Boris. "Kogia breviceps." Convention on Migratory Species. http://www.cms.int/reports/small_cetaceans/data/K_breviceps/K_breviceps.htm (accessed on July 8, 2004).

Whale and Dolphin Conservation Society. http://www.wdcs.org (accessed on July 8, 2004).