Grey Whale (Eschrichtius robustus)

              

Class:	Mammalia
Order:	Cetacea
Family:	Eschrichtiidae
Size:	Length 30 to 49 feet (9 to 15 m)
Weight:	25 to 40 tons (23 to 36 metric tons)
Diet:	Bottom-dwelling invertebrates
Distribution:	North Pacific Ocean, North Atlantic Ocean and Arctic Ocean
Young:	1 calf every 2 years
Animal Predators:	Killer whale
IUCN Status:	Critically Endangered/ Lower Risk, Conservation Dependent (See Conservation section below for explanation)
Terms:	Young: Calf   Group: Pod
Lifespan:	40 to 50 years

 

Facts/Trivia:

·         Grey whales have been hunted by humans for their oil, meat, hide, and baleen.

·         Grey whales breach often, leaping up and splashing back down into the water.

·         The grey whale is known by various names including “devilfish,” “grey back” and “mussel digger.”

·         The scientific name comes from Eschrichtius, which is the name of the Danish professor who worked with these animals and robustus, which is Latin for “strong.” 

 

Description

Grey whales have a streamlined body with a narrow, tapered head. They host a large amount of parasites, carrying both barnacles and whale lice, giving these whales a mottled appearance. Otherwise, their skin is uniformly light to dark grey with no other markings, although there have been occasional albinos. Females tend to be larger than males. Grey whales are baleen whales, which means that instead of teeth, they have a row of plates in their mouth known as baleen that they use to filter their food. Baleen is made of keratin, a flexible material also found in fingernails and hooves that becomes frayed at the tips. They have two to five grooves on their throat which allows them to expand their throat during feeding. Their upper jaw—which has dimples with hair growing from the depressions—slightly overlaps their lower jaw. Their flippers are shaped like pointed paddles and their fluke is about 12 feet (3.7 m) across, pointed at the tips, and deeply notched in the centre. Grey whales do not have a dorsal fin but they do have two blowholes located at the top of their head. 

 

Habitat

These medium-sized whales once ranged throughout both the North Pacific Ocean and the North Atlantic Ocean. They have also been spotted in the Arctic Ocean. Led by pregnant females, many grey whales will migrate south along the coast of North America. The whales follow the shoreline, and do something called “spy-hopping,” in which a whale pushes its head straight up out of the water and then sinks its body slowly back down. It is believed they do this to take a look at the nearby shore. The migrations are extremely long (up to 20,400 km or 12676 miles per round trip), so not all whales migrate.

 

Feeding Habits

Grey whales feed at the sea’s bottom by sucking in the small marine animals that dwell there in the sediment and then straining the excess water and mud through the bristly baleen plates on the jaws, leaving behind only the food. During the entire feeding season, the whales store up enough fat to last them throughout the breeding season, when they rarely feed. By the time the whales return to their feeding ground, they have lost up to one-third of their body weight. 

 

Reproduction

After a 13-month pregnancy, females give birth in the south, off the coast of California and Mexico. Calves measure 15 feet (4.6 m) long and weigh 1,500 pounds (680 kg) when born. Newly-born whales do not have thick enough coats of blubber to withstand cold arctic water, so they remain in the tropical lagoons, feeding from their mother’s rich milk (which contains 53 percent fat) for seven months before venturing north with the rest of the whales in the spring. They are weaned shortly after arriving in their summer grounds. Females are extremely protective of their offspring. 

 

Behaviour

Grey whales usually swim no farther than two or three miles from the shore, making them popular tourist attractions throughout their range, and in earlier times, popular with whalers. At a cruising speed of four to five miles (7 to 9 km) per hour, these whales are slower swimmers than other whales. Migrating grey whales have predictable breathing patterns, generally blowing three to five times in 15 to 30 second intervals before raising their fluke and then diving underwater for a few minutes. Grey whales can stay submerged for up to 15 minutes. They live in pods of about three whales, though some pods have up to 16 members. 

 

Conservation

Grey whales in the Northeast Pacific are considered Lower Risk, Conservation Dependent by the IUCN, while the Asian, or Northwest Pacific stock are considered Critically Endangered, with a population estimated to number less than 50 mature individuals. Whaling was the main cause of the grey whale’s decline. In 1946, commercial hunting of grey whales was prohibited by the International Whaling Commission. Since then numbers have increased to several thousand, but they are still considered endangered. The Atlantic population is listed as Extirpated by Environment Canada. 

 

Sources

http://animaldiversity.ummz.umich.edu/accounts/eschrichtius/e._robustus$narrative.html

http://www.acsonline.org/factpack/graywhl.htm

http://whales.magna.com.au/DISCOVER/GRAY/

http://www.enchantedlearning.com/subjects/whales/species/Graywhale.shtml

http://www.speciesatrisk.gc.ca/Species/English/SearchDetail.cfm?SpeciesID=129

http://www.tmmc.org/learning/education/whales/gray.asp

http://www.oceanoasis.org/fieldguide/esch-rob.html

Gray Whale Wildlife Fact File, IM Pub, US