Beaked Whales: Ziphiidae

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BEAKED WHALES: Ziphiidae

NORTHERN BOTTLENOSED WHALE (Hyperoodon ampullatus): SPECIES ACCOUNTS
SHEPHERD'S BEAKED WHALE (Tasmacetus shepherdi): SPECIES ACCOUNTS

PHYSICAL CHARACTERISTICS

Beaked whales are the second largest family of living whales. They get their name from their long, narrow snout, or beak. In some species, the snout slopes gradually into the forehead. In others, the forehead bulges out over the beak. Beaked whales breathe through a blowhole on top of their head. They have a melon, a fatty organ in their forehead that they use for echolocation (eck-oh-loh-KAY-shun).

Beaked whales are toothed whales. However, all species except Shepherd's beaked whale have very few teeth. Males usually have only one or two teeth in the lower jaw and just stubs or no visible teeth at all in the upper jaw. The lower jaw teeth grow into tusks in some species. In females of some species, the teeth never erupt, or break through the skin, although in x rays they can be seen in the jaw.

Beaked whales are medium-sized whales ranging from about 13 to 42 feet (4 to 13 meters) in length and weighing up to 25,000 pounds (11,500 kilograms). They have cigar-shaped bodies that are thicker in the middle than at either end. Their dorsal (back) fin is small and set farther back toward the tail than in other whales. The bones in what would be the hand and arm of a land animal are compressed into a web of bone to make small flippers that fit against their body in depressions called flipper pockets. The back legs are so reduced that all that remains are a few internal pelvic bones. Beaked whales have strong, muscular tails that, unlike most other whales, are not notched. They range in color from light brown to gray to black. Males and females may have different color patterns.

GEOGRAPHIC RANGE

Beaked whales live in every ocean of the world. The only place they are not found is under the permanent ice pack at either pole.

HABITAT

Beaked whales are mainly deep water whales. They can be found beyond the continental shelf in water as shallow as 660 feet (200 meters) and as deep as 9,900 feet (3,000 meters). Most live at depths of 3,300 to 9,900 feet (1,000-3,000 meters). These whales are often found around underwater formations such as canyons, shelf edges, and seamounts. A seamount is an underwater mountain that does not break the surface.

DIET

Beaked whales are good divers. Scientists believe that they feed on squid, fish, shrimp, and crabs that live on or near the ocean floor, because they have discovered these animals plus stones in the stomachs of dead beaked whales.

Beaked whales have well-developed melons and use echolocation to find and catch their prey. Echolocation involves making sounds or clicks that are then focused through the melon and skull. These to sounds 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. This is particularly useful, since little sunlight penetrates to the depths where these animals feed.

Since beaked whales have few teeth, they feed by sucking in their food. They have up to six groves in their throat that can expand and along with their strong tongue suck prey into their mouth. These whales also have between four and fourteen chambers, or sections, to their stomach.

BEHAVIOR AND REPRODUCTION

Not too much is known about beaked whale behavior or reproduction, because these animals live mainly in the open ocean and are hard to observe. They usually are seen in pods (groups) of ten or fewer animals, and within a pod they seem to swim or dive all at the same. This suggests that like other cetaceans, they have a good communication system. Some species regularly migrate, while others seem to stay within a home range.

From the scars that appear on the skin of some males, it appears that they fight each other with their tusks for the right to mate with females. One calf is born at a time. It stays with the mother and nurses for at least one year.

BEAKED WHALES AND PEOPLE

Three species of beaked whale were hunted mainly from the 1880s to the 1920s for their oil and spermaceti: the northern bottlenosed whale, Cuvier's whale, and Baird's whale. Otherwise beaked whales have few interactions with humans because they live so far off shore.

STRANDED ON LAND

Scientists cannot explain why whales strand themselves on shore. Individual whales that strand are usually old or sick. However, sometimes whole pods, meaning dozens of animals, will strand at once. Usually these are deep-water toothed whales. Some scientists believe that their echolocation system does not function well when they accidentally stray into shallow water. Others think the whales are escaping a predator or are frightened by human-made underwater noises. Another theory is that disease or pollution makes them disoriented. Whatever the reason, people have recorded strandings for hundreds of years all over the world. Stranded animals that cannot be re-floated often die because they are so heavy out of water they cannot expand their lungs to breathe.

CONSERVATION STATUS

Not enough is known about most species of beaked whale to give them a conservation rating. However, four species, the northern bottlenose whale, the flathead bottlenose, Baird's beaked whale, and Arnoux's beaked whale, although not vulnerable to extinction, are listed as in need of conservation efforts.

NORTHERN BOTTLENOSED WHALE (Hyperoodon ampullatus): SPECIES ACCOUNTS

Physical characteristics: The northern bottlenosed whale is also called the Atlantic bottlenosed whale, the flathead, or bottlehead. Males reach a maximum length of about 30 feet (9 meters), while females grow only to about 25 feet (7.5 meters). In addition, males develop a large, bulging forehead. The forehead of the female is much smoother. Both sexes have a short beak or snout and range in color from dark brown on the back to pale yellow on the belly. Mature males often have a white or light patch on the forehead. Males have one pair of small teeth in the lower jaw. In females, the teeth never break through the skin.

Geographic range: These whales are found in pockets in the North Atlantic off Norway, Finland, Greenland, Iceland, and as far south as Spain and North Africa on the European side. On North American side, they are found off the Labrador and Nova Scotia in Canada and as far south as Rhode Island in the United States. One particularly well-studied group lives in an area called the Gully, a deep canyon off Sable Island, Nova Scotia.

Habitat: Northern bottlenosed whales prefer deep, cold to moderate (32 to 63°F; 0 to 17°C) water, and sometimes travel into broken ice fields. They are usually seen in areas where the water is more than 3,300 feet (1,000 meters) deep and are more common in the northern part of their range than in the southern part.

Diet: Northern bottlenosed whales feed near or at the ocean floor. They eat mainly squid, but will also eat fish, sea cucumbers, starfish, and shrimp. Like all toothed whales, they use echolocation to hunt their prey.

Behavior and reproduction: Northern bottlenosed whales live in groups of four to ten individuals. They are excellent deep divers and have been known to regularly dive to depths of between 2,600 and 4,600 feet (800-1400 meters) and stay under water for seventy minutes. These whales seem to migrate north in the summer and south in the winter in a regular pattern.

Not much is known about bottlenosed whale reproduction, although it is believed that males buck each other in the head in competitions to breed with females. Females are thought to be sexually mature (able to reproduce) at about seven to ten years old. A single calf is born in the spring or early summer after a twelve-month pregnancy. It stays with its mother and nurses for at least one year. Northern bottlenosed whales are thought to live for thirty to forty years.

Northern bottlenosed whales and people: These whales have few interactions with people.

Conservation status: These whales were hunted from the 1880s until the 1970s, mostly in Norway. One estimate is that Norwegian fisherman killed 60,000 northern bottlenosed whales between 1880 and 1930 and 5800 from 1930 to 1973. Hunting stopped in 1973, and in 1977 the whale became legally protected from hunting. Another threat to this species is human development. In Nova Scotia, a large undersea oil and gas field is being developed only about 3 miles (5 kilometers) from the Gully where these whales live. ∎

SHEPHERD'S BEAKED WHALE (Tasmacetus shepherdi): SPECIES ACCOUNTS

Physical characteristics: Shepherd's beaked whale, also called the Tasman beaked whale, has not been well studied. What is known about it comes mainly from about twenty stranded whales that have been found in various places in the Southern Hemisphere.

Shepherd's beaked whale is the only whale in this family to have more than half a dozen teeth, It has about 90 to 100 small peg-like teeth in both the upper and lower jaw. Two teeth in the lower jaw of males develop into tusks. Shepherd's beaked whale is about 23 feet (7 meters) long. It has a dark brown or gray back, two light stripes along its side and a light cream-colored belly.

Geographic range: These whales are found in temperate (moderate) water from Chile to South Africa to New Zealand.

Habitat: Shepherd's beaked whale lives in deep water in open ocean.

Diet: Unlike other members of this family that eat squid, the Shepherd's beaked whale appears to eat mainly fish.

Behavior and reproduction: This whale was not discovered until 1937. It is very rare. Almost nothing is known about its behavior or reproduction.

Shepherd's beaked whale and people: There have been only about half a dozen sightings of this whale outside of strandings.

Conservation status: Not enough information is available to give this whale a conservation ranking, although the absence of sightings suggests that it is rare. ∎

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)