Gray Whales Essay

Gray Whale

Physical Description
The Gray Whale, or Eschrichtius robustus, has a smooth, oval-like shape, and is known for its mottled, gray coloring. Its head is slightly tapered off, and the upper jaw overlaps the lower jaw a little bit. They are baleen whales, so instead of teeth, they have a row of stiff plates made out of keratin, the material our fingernails are made of. Gray Whales are prone to some types of skin diseases, such as Orange Whale Lice, and can grow barnacles on their skin. They have bilateral symmetry, which means their body could be cut in half, and look the same on both sides. This type of whale can range from 12.192 - 15.24 meters in length, and can weigh up to 27.25 - 36.28 metric tons. Gray Whales are mostly spotted breaching. Breaching is when they leap partially out of the water, and fall back in the water.

Habitat
Gray Whales live in a relatively shallow part of the Pacific Ocean most of the time, called the Neritic Zone. The Neritic Zone is about 200 meters deep, and houses most ocean organisms. They live along the North American West Coast and the Eastern coast of Asia. They live alone, or in pods, small groups of whales. In

the winter months, Gray whales stay in shallow waters along coastlines with muddy or sandy floors. During summer, they tend to stay in waters with a maximum depth of 60 meters and close to the shore. In the fall, the whales migrate south to warmer waters along the west coast of North and South America.

Diet
As expected, Gray Whales need to eat a lot to stay healthy.

It is estimated that they eat about 1,089 kilograms of food a day during the 140-300 day feeding period they have once a year. That comes to a total of about 150,000 kilograms of food consumed by one whale. Their diet consists mostly of small crustaceans, like shrimp and krill, plankton, tube worms, and mollusks. To eat, they go to the bottom of their feeding grounds, roll on their sides, and traps the stirred up sediment in their mouths. Then, their baleen plates filter out the sediment, and send the food down their throats. The main predators of Gray Whales are Orcas, large sharks, and humans. They were on the U.S. endangered species list until 1994. As of now, Gray Whales have a healthy population of 19,000

whales.

Reproduction
Like all mammals, Gray Whales reproduce sexually. Their gestation period lasts 12-13 months, and mostly one calf is born at a time. There is no specific mating season, calves are born at all times of the year. Calves and their mothers stay together for about a year. Gray Whale calves nurse for about 7-8 months. They are known for being wonderful mothers, and take good care of their babies. After a calf is born, the baby and its mother spend 2 months in a lagoon to build up a layer of blubber on their young body. Then, the pair migrates to feeding grounds up north to wean the calf off of its mother.