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  ScienceZoologyMammalsOrder Cetacea
 
Gray WhaleGray Whale

Eschricktius robustus

Description

The gray whale's name comes from the numerous gray patches and white mottling on its dark skin. Most gray whales are also marked with many scratches, scattered patches of white barnacles, and orange whale lice. Newborn calves are dark gray to black.

The gray whale's upper jaw is narrow and slightly arched. It has no dorsal fin, but does have a prominent dorsal hump about 2/3 of the way down the back, followed by 9-12 knobs. The flippers are paddle shaped and pointed at the tips. The fluke is 10-12 feet across, pointed at the tips, and deeply notched in the center.

Adult males are 45-46 feet long on average, and weigh 30-40 tons. Females are slightly longer than males, but weigh about the same.

Gray whales have the coarsest baleen of all whales, with only about 20 bristles per inch of plate (compared to over 100 per inch in sei whales). amd 130-180 plates on each side of the jaw.

Distribution and Habitat

distribution of the gray whaleGray whales live in the shallow coastal waters of the eastern North Pacific. There used to be a population in the western North Pacific, but it is now extinct.

Gray whales leave their feeding grounds in October and make their way to breeding and calving grounds off the coast of Baja California. The journey takes about 2-3 months, and they will remain their for another 2-3 months. One of the longest migrations of all mammals, the gray whales will have traveled 10,000-14,000 miles by the time they return to their feeding grounds.

Diet

Like all other baleen whales, the gray whale is a filter feeder. Unlike other baleen whales, however, it feeds on the ocean bottom, rather than straining nutrients out of the sea directly. To feed, a gray whale dives to the bottom, rolls on its side, and draws bottom sediments and water into its mouth. As it closes its mouth, water and sediments are expelled through the baleen plates, while small crustaceans are trapped on the inside.

Reproduction

A female gray whale gives birth to one calf every other year, on average. Twins are not unheard of, but are extremely rare. The calf is born after a gestation period of 12-13 months. It is about 15 feet long and weighs 1,100-1,500 pounds at birth, and can swim within 30 minutes. It is weaned at 7-8 months.

Gray whales reach sexual maturity at 5-11 years, or when they reach a length of 36-39 feet. Average lifespan is 4-50 years in the wild.

Other Behavior

Gray whales are not very social animals. They generally congregate in loose pods of 3-16 whales, but form no long-term bonds.

Although an agile swimmer, a gray whale seldom travels faster than 2-6 mph; it can, however, go up to 10-11 mph in bursts when in danger. It can dive to a depth of 500 feet and stay submerged for up to 30 minutes, and can swim in relatively shallow water without running aground.

Scientific Classification

phylum Chordata
subphylum Vertebrata
class Mammalia
order Cetacea
suborder Mysticeti
family Eschrichtiidae
genus & species Eschrichtius robustus

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  The Robinson Library > Science > Zoology > Mammals > Order Cetacea

This page was last updated on December 01, 2014.

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