Beluga and Narwhal: Monodontidae

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BELUGA AND NARWHAL: Monodontidae

BELUGA (Delphinapterus leucas): SPECIES ACCOUNTS
NARWHAL (Monodon monoceros): SPECIES ACCOUNTS

PHYSICAL CHARACTERISTICS

Beluga whales and narwhals are the only two living species in this family. Although they look quite different, these species share certain physical characteristics, including a very small beak and small head. Their neck bones (cervical vertebrae) are not fused or joined together, giving them the ability to turn their head without turning their entire body. Neither species has a dorsal (back) fin, only a ridge where the fin normally is found. The lack of a fin is unusual in whales. Members of this family range in size from 13 to 16 feet (4 to 5 meters) and in weight from 1,500 to 3,500 pounds (680 to 1,600 kg).

Both species change color as they age. Belugas are born gray, but gradually become white by the time they reach maturity at seven to nine years. Narwhals are born gray. As young animals, they become almost completely blue-black. In adulthood they become mottled (spotted) dark gray, with more dense splotches on the back and less dense ones on the belly. In old age, they become white.

The main difference in these species is in their teeth. Belugas have simple teeth in both the upper and lower jaw. Narwhals have only two teeth in the upper jaw. In females, these teeth do not erupt or become visible. In males, one tooth becomes a spiraled tusk that may be 10 feet (3 meters) long.

GEOGRAPHIC RANGE

Both these species live in the Arctic oceans, although their distribution is not continuous.

HABITAT

Narwhals live in deep water farther north than any other whale, following the ice pack as it grows and recedes. Beluga whales live in shallower water and are sometimes found farther south. In the summer, they move into estuaries (places where rivers empty into the ocean). They can survive in fresh water and have occasionally been found swimming hundreds of miles (kilometers) up river from the ocean.

DIET

Both these species are bottom feeders, diving deep to eat squid, fish, and shrimp. Narwhals have a more limited diet than belugas.

BEHAVIOR AND REPRODUCTION

Both narwhals and beluga whales live in small groups or pods, although these pods may gather in groups of hundreds or thousands of animals during migrations. These species are social and communicate with a wide range of sounds. Both species migrate. The narwhal follows the ice pack, moving north as it melts in summer and south as it grows in winter. The migration of belugas appears to be triggered by day length. Not all groups of belugas migrate. One well-studied group that live at the mouth of the St. Lawrence River in Canada appears to stay there year round.

These whales give birth to a single calf at a time after a pregnancy lasting thirteen to sixteen months. The calf nurses, feeds on breast milk, and remains dependent on its mother for up to two years. Mating usually occurs in late winter or early spring and births occur in the summer of the following year.

BELUGAS, NARWHALS, AND PEOPLE

The native people of the Arctic, the Inuit, have hunted narwhals and beluga whales for hundreds of years. These animals are an important part of their diet and culture. Both species have also been hunted commercially.

NOW THAT'S FAT!

In order to keep from freezing in the from cold Arctic water, beluga whales are covered with a layer of blubber that is 10 inches (25 centimeters) thick. This fat makes up half of the animal's weight or on average 1,700 pounds (800 kilograms) of fat.

CONSERVATION STATUS

Beluga whales are considered Vulnerable, facing a high risk of extinction, dying out. Not enough is known about the size of the narwhal population to give them a conservation rating. All narwhals that have been taken into captivity have lived only a few months. However, beluga whales do well in captivity and are often exhibited at marine parks.

BELUGA (Delphinapterus leucas): SPECIES ACCOUNTS

Physical characteristics: Beluga whales, sometimes called white whales, begin life colored light gray, then turn darker gray and become white as they mature. They are the only species of whale that is completely white. Beluga whales range in length from 13 to 16 feet (4 to 5 meters) and in weight from 1,500 to 3,500 pounds (700 to 1,600 kilograms). Males are about 25 percent larger than females.

Geographic range: These whales are found worldwide in the Arctic. Isolated populations also exist in the Gulf of St. Lawrence, Canada, and in Cook Inlet, Alaska.

Habitat: Belugas live in cold water of almost any depth. During the summer they gather in shallow water at the mouths of rivers. At other

times, they migrate through deep, open ocean. They can survive in fresh water, and have been occasionally found in rivers far from the ocean.

Diet: Belugas eat a wide variety of squid, fish, crabs, shrimp, clams, worms, and octopus that they find by echolocation (eck-oh-loh-KAY-shun). They can easily dive to depths of 3,300 feet (1,000 meters). Their teeth are not made for capturing prey. Instead, they suction food into their mouths and swallow it whole.

Behavior and reproduction: Belugas are some of the most playful whales. They have been seen swimming and playing either alone or with other whales with all kinds of floating objects. They live in pods of less than ten animals, but these pods often gather into large herds of hundreds of animals.

Belugas are the most vocal species of whale. Their voices are loud and varied. They make clicks, chirps, whistles, squawks, and other high-pitched sounds.

Mating occurs in early spring and a single calf is born about fourteen months later. During the summer, females gather in shallow waters at the mouths of rivers to give birth, probably because the water there is warmer than in the open ocean. Calves nurse for about two years. A new calf is normally born every three years. Belugas are thought to live between thirty-five and forty years in the wild.

Natural predators, animals that hunt them for food, of the beluga whale include killer whales and polar bears. Polar bears lie in wait at breathing holes in the ice and attack when the whale surfaces to take a breath.

Beluga whales and people: Belugas have been hunted commercially for food mainly by the Russians. They adapt well to captivity and are also captured for display in marine entertainment parks. Ecotourists visit the population in the St. Lawrence River to observe them in their natural environment.

Conservation status: Beluga whales are considered Vulnerable. Some populations, like the one at the mouth of the St. Lawrence River are coming under increasing pressure from chemical pollution, shipping, and the development of undersea oil and gas fields. ∎

NARWHAL (Monodon monoceros): SPECIES ACCOUNTS

Physical characteristics: Narwhals grow to be about 14 to 15.5 feet (4.2 to 4.7 meters) long and weigh 2,200 to 3,500 pounds (1,000 to 1,600 kilograms). Males are much larger than females.

The most outstanding physical feature of the narwhal is its ivory tusk. The tusk is a tooth that in males grows out of the left side of the upper jaw in a counter-clockwise spiral. Tusks can grow to be one-third the length of the body, or 30 feet (10 meters) long, and weigh 20 pounds (10.5 kilograms). Narwhals have two teeth in the upper jaw, and occasionally the right tooth will also grow into a tusk. Once in a great while, a female will develop a tusk. Tusks are often broken, but will heal and continue to grow.

Geographic range: Narwhals are limited to the coldest Arctic waters. They are not evenly distributed and are rare along Alaska, Siberia, and parts of Arctic western Canada.

Habitat: Narwhals live in colder water than any other whale. They follow the ice pack, moving north in the summer as it retreats and south in the winter as it grows. They often swim long distances under thick ice, coming up to breathe in small cracks called leads.

Diet: Narwhals feed along the sea bottom, eating squid and deep water fishes. They can dive to depths of about 3,300 feet (1,000 meters) and stay under water for up to twenty-five minutes. They locate their food by echolocation. Echolocation involves making sounds that bounce off objects. Sense organs pick up the echo or reflected sound and use information about its the timing, direction, and strength to determine the location of objects.

Behavior and reproduction: Narwhals are social animals. They live in groups or pods of three to eight individuals, usually of the same sex and age. When they migrate, these pods may gather to form groups of hundreds or even thousands of animals. Narwhals have been known to work cooperatively to open breathing holes in the ice. Several animals will simultaneously butt their foreheads against the ice sheet in order to break it. This suggests that they have some form of group communication.

Narwhals mate in the early spring and have a single calf in July or August of the following year. Scientists are not sure, but they think that males fight each other with their tusks for the right to mate. Females normally produce a calf every three years. Pregnancy lasts about fifteen months. Newborns are 5 feet (1.6 meters) long and weight about 175 pounds (80 kilograms). They are born with a 1-inch (2.5-centimeter) thick layer of blubber to protect them from the cold water. Calves nurse for about twenty months and may remain with their mother longer. They become physically mature between four and seven years of age and can live fifty years in the wild. Natural predators of the narwhal are the killer whale and the Greenland shark.

Narwhals and people: The ivory in the tusks of narwhals has commercial value. It is often carved into jewelry or decorations. The tusks are also sold as curiosities to collectors. In earlier times, narwhal tusks brought back by sailors may have given rise to the story of the unicorn, a one-horned horse.

Conservation status: Not enough is known about the population of narwhals to give them a conservation ranking. Threats include being hunted for food and for their tusks. Global warming is of particular concern to the survival of this species, because they live in and around the ice pack. ∎

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).