Gray Whale: Eschrichtiidae

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GRAY WHALE: Eschrichtiidae

PHYSICAL CHARACTERISTICS

Gray whales are very large animals that weigh 30 to 40 tons (27,200 to 36,300 kilograms) and are 45 to 50 feet (13.8 to 15 meters) in length. Females are larger than males. These whales have a streamlined body with a narrow head. The upper jaw overlaps with the lower jaw, and they have two to four throat grooves. Each groove is about 5 feet (1.4 meters) long and allows the throat to expand when the whale takes in water for filter feeding.

Gray whales are baleen (buh-LEEN or BAY-leen) whales. They do not have teeth. They filter feed using 130 to 180 overlapping plates called baleen plates that hang from the upper jaw. These plates are made of a material called keratin (KARE-ah-tin). This fingernail-like material frays out into thin hairs at the end of each strand to make a strainer. Each baleen plate is white and about 2 to 10 inches (5 to 25 centimeters) in length.

Gray whales have a 10-inch (25-centimeter) layer of blubber, or fat, to keep them warm in freezing cold water. Their skin is dark with gray patches and white splotches. Their skin also shows many scars and patches from white barnacles and orange whale lice. Often many more of these patches are found on the left side of the whale than on the right because of the way the whale scrapes along the ocean floor while feeding.

Although the gray whale does not have a dorsal (back) fin, it does have a large dorsal hump about two-thirds of the way back on its body. Behind the hump is a row of six to twelve knuckles that extend to its fluke, otherwise known as its tail. The fluke is 10 to 12 feet (3.7 meters) across with a deeply notched center and pointed tips. The flippers are shaped like paddles and are also pointed at the tips.

GEOGRAPHIC RANGE

Gray whales migrate between northwest Alaska in the Chukchi Sea, where they live during the summer, and the Baja Peninsula of Mexico, where they live during the winter. A few individual gray whales live year-round in the Straits of Juan de Fuca, located between the state of Washington and Vancouver Island, Canada, and off the coast of California. Most whales, however, make the 10,000-mile (16,000-kilometer) trip from Mexico to the Arctic yearly.

HABITAT

Gray whales prefer shallow coastal water but dive to the ocean floor to feed. Every year gray whales spend two to three months migrating 10,000 miles (16,000 kilometers) from their summer home in Alaska to the warmer coastal waters off of the Baja Peninsula, Mexico, where they stay all winter.

DIET

Gray whales eat a variety of small shrimp, krill, squid, and octopus, along with plankton and mollusks. They are seasonal feeders, doing most of their feeding between May and November in the Arctic, but they are unique among baleen whales because they are bottom feeders. To eat, they dive to the bottom and roll on to their right side. They suck the stirred-up bottom mud and water into their mouth. This is filtered through the whale's baleen plates, trapping the food near the tongue where it can be eaten.

DEVIL FISH

Gray whales got the nickname "devil fish" from early whalers who hunted off the coast of the Baja Peninsula. They got this name because the gray whale mother is so protective of its calf. The mother will make any sacrifice, including death, to protect her young. Soon whalers found that it was too dangerous to hunt these whales from boats in the water, so they started a new technique where they would herd the whales toward the beach and harpoon them from land.

BEHAVIOR AND REPRODUCTION

Gray whales live in small groups (called pods) of about three whales, although some pods may have as many as sixteen whales. In feeding waters, pods come together, and hundreds of whales will temporarily feed in the same area.

Although gray whales are large, they are quite agile. Normally gray whales swim only 2 to 6 miles per hour (3 to 10 kilometers per hour), but when in danger, they can reach speeds of 10 to 11 miles per hour (16 to 17.5 kilometers per hour). While feeding, gray whales usually swim at speeds of 1 to 2.5 miles per hour (1.6 to 4 kilometers per hour).

Gray whales can do many different maneuvers (mah-NOO-verz) including breaching, where they jump partially out of the water and fall back in at an angle. This makes a loud noise and is thought to either help clean off some of the barnacles and lice on their skin or to communicate with other gray whales. Spy hopping is another favorite maneuver. This is when the whale pokes its head up to 10 feet (3 meters) out of the water and looks around while turning slowly.

Gray whales can stay underwater for thirty minutes and dive to depths of 500 feet (155 meters) while searching for food. When they come back to the surface, they take in air through two blowholes located near the top of their head. Before they go under water for a long time, they spend two to five minutes taking deep, slow breaths. When at rest, gray whales breathe about two to three times per minute. While sleeping, they keep their blowhole just above the surface. Each spout, or breath, is very noisy and can be heard up to a half mile away. The stream of water that comes from the blowhole rises 10 to 13 feet 3 to 4 meters) above the water and is a very impressive sight.

Gray whales reach sexual maturity when they are about 36 to 39 feet (11 to 12 meters) long. This usually occurs between five and eleven years of age. Courtship and mating involves three or more whales of both sexes and is very complex. Both mating and calving usually occur off the coast of Baja California, Mexico. After breeding, which usually takes place in late winter or early spring, females are pregnant for twelve to thirteen months. When the calf is born, it is about 15 feet (4.5 meters) long and weighs somewhere between 1,100 and 1,500 pounds (500 to 600 kilograms). The calf spends seven to eight months nursing on its mother's milk, which is 53 percent fat. Females have a single calf only every two to four years.

A LONG TRIP

Gray whales migrate 10,000 miles every year between Alaska and Mexico. This is the longest migration of any mammal. During this time, they do not eat, but live off their stored blubber.

When the calf is born, it immediately swims to the surface. Its mother helps it, because the newborn cannot swim for the first half hour of its life. Gray whales stop growing at the age of forty and usually live to be between fifty and sixty years old.

Gray whales do not have many predators, animals that hunt them for food. The largest and most significant are humans, who spent thousands of years hunting these whales almost to extinction. Killer whales, also known as orcas, will attack gray whales and often kill them. Killer whales make most of the scars on the backs of gray whales. Most of these attacks happen off the coast of northwest Oregon. Large sharks have also been known to attack gray whales, but that is much less common.

GRAY WHALES AND PEOPLE

For thousands of years, people have hunted the gray whale for oil, meat, hide, and baleen. This has caused a major decline, and two of the three populations located throughout the world were killed off. As the gray whale became protected by the International Whaling Commission, whale watching has replaced hunting. Now millions of people watch gray whales along the peninsula of Baja California and as they migrate along the West Coast of North America. Some gray whales are known as "friendlies" and will come up to small boats and allow themselves to be touched.

CONSERVATION STATUS

At one time there were three separate gray whale populations in the world. A population in the North Atlantic became extinct during the mid-1700s because of overhunting. The western Pacific population was also overhunted to extinction in the 1930s. Now, only the eastern Pacific stock remains. These whales were hunted almost to extinction in the 1850s. In 1937, the International Whaling Commission gave the gray whale partial protection, and in 1947 this was changed to full protection. The Eastern Pacific gray whale population has made an extraordinary recovery. Their numbers now range between 19,000 and 23,000 individuals. This number is close to their original population.