Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetartiodactyla
Family: Eschrichtiidae

Genus/species: Eschrichtius robustus

GENERAL CHARACTERISTICS: This species is mottled dark to light grey and is encrusted with patches of barnacles and orange whale lice. Unlike Humpback whales, Grey whales lack a dorsal fin and instead has a series of bumps along a dorsal ridge on the final third of the back. Gray whales have small, paddle-shaped flippers, compared to the large white flippers of Humpback whales.
Length to 14 m (46 ft).
Weigh to 36,000 kg (79,300 pounds).

(see links below for live animal photos under references).

Grey Whale18204939731_f69eecb43a_k

DISTRIBUTION/HABITAT: Now found only in the North Pacific and adjacent waters. E. robustus are primarily bottom feeders and are thus restricted to shallow continental shelf waters for feeding.

DIET: The only cetacean to feed by straining the sediment on the sea floor. mainly for bottom-dwelling crustaceans but also worms and mollusks. Water, sand and mud are expelled through the baleen and food is then swallowed.
Sufficient fat reserves are stored in the feeding grounds to allow individuals to go without food during the breeding season; on return to the feeding grounds about a third of the body weight may have been lost.

REPRODUCTION: The breeding cycle last two years. Gestation takes about 13 months and the single calf is then suckled for a further seven months. The mother may have to hold the calf near the surface to help it to breathe during the first few hours after birth.

E. robustus makes the longest migration of any mammal known, each autumn and spring they pass between their Arctic summer feeding grounds and the mating and calving lagoons in Baja California.
Round-trip up to 20,400 kilometres (12,676 miles).

LONGEVITY: 25 to 80 years.

PREDATION: The only non-human predator of Gray whales is the Killer whale with up to 18% of all Gray whales showing evidence of an Orca attack.

The Eastern North Pacific population has made a significant recovery since 1947 when whaling stopped for this species and now they number between 19,000 – 23,000, which may be close to their original population size.
Three gray whale breeding lagoons in Mexico enjoy some protection in the form of limitations on boating, fishing and coastal development.

Threats: Collisions with ships, entanglement in fishing nets and pollution. Habitat degradation resulting from drilling and dredging is also a problem.

REMARKS: The California Academy’s Gray whale was a juvenile that beached in Baja California in 1966. It would have been about 35 feet long while alive. The two small, hanging, isolated bones towards the tail are remnants of pelvic bones, evidence that whales descended from four-legged land mammals that returned to the ocean about 53 million years ago.


California Academy of Sciences Docent program Whale  information March 2015

IUCN Red List


Ron’s flickr link…

Shirihai, H & Jarrett (2006) Whales Dolphins and Other Marine Mammals of the World Princeton University Press.

Evans, P & Weinrich, M (2002) Whales Dolphins and Porpoises D K London New York Munich Melbourne and Delhi.

Reeves, R, R, et al (2002) Guide to Marine Mammals of the World  Chanticleer Press, Inc.

Ron’s WordPress Shortlink