This energy is then passed through food webs from one organism to the next. On land, plants capture the sun's energy, are the base of food webs, and constitute the largest physical bulk of the living world. Cell for cell, planktonic algae fix more solar energy and manufacture more protoplasm than plants on land. Seabirds drink seawater that has a salt content three times greater than the bird's body fluids. Salt glands remove salt from the blood and restore the normal salt content of body fluids rapidly after seawater is consumed.
Gray whales undertake the longest annual migration of any mammal.
Each year in the Eastern Pacific, gray whales migrate 20,000 kilometers between their feeding areas in the Bering and Chukchi seas, and their breeding and calving grounds in the coastal lagoons of Baja California. With pregnant females leading the way and other adults and yearlings following, they cross the Gulf of Alaska at a rate of about 185 km per day. Unlike most other large cetaceans, gray whales are a coastal species generally associated with the continental shelf. The species represents one of the Endangered Species Act's success stories. The gray whale was listed as endangered throughout its range in 1970.