Gray Whale: Eschrichtiidae
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.
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.
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