Marine mammals spend all or the majority of their time in water, and thus are specially adapted to this way of life. Their thick layers of fat help to keep them warm in frigid waters. Since they are mammals, they must always come up to the surface to breathe, although they can often hold their breath for surprising lengths of time.
Whales, dolphins and porpoises are all part of the order Cetacea. This order is broken down into two suborders, the first of which is Mysticeti, the baleen (or "moustached") whales. There are at least 10 living species included in this group. The second suborder includes toothed whales and their relatives.
Baleen whales are so named because they have "baleen (bay-leen)" in place of teeth. Rows of baleen are rooted in the roof of the mouth of the whale, like the teeth of a comb. Baleen whales take in water, either by gulping, sucking, or swimming with their mouths open, and this water contains their food (often plankton, krill, or small fish). The bristles of the baleen trap the food as it passes. The size and structure of the baleen in each type of whale varies depending on the food source of the whale.
Baleen whales are also differentiated from the toothed whales by the presence of two external blowholes; toothed whales have one blowhole.
The most common of the baleen whales found in waters near Togiak National Wildlife Refuge is the gray whale. Minke whales (Balaenoptera acutorostrata) are less frequently sighted; sei whales (Balaenoptera acutorostrata) have been seen on Togiak Refuge only very infrequently.
Gray whale (Eschrichtius robustus):
The body of the gray whale is a mottled gray color, and usually appears bumpy due to the presence of many barnacles and "whale lice." Gray whales have a narrow head, heart-shaped blowhole, and lack a dorsal fin. They are up to 46 feet in length, weighing up to 35 tons. Females are usually larger than males of the same age.
Gray whales have one of the longest migrations recorded for any mammal, wintering off of Baja California and mainland Mexico, and spending May to November feeding in the Bering, Beaufort, and Chukchi seas. Their main food sources are benthic amphipods. Gray whales are preyed upon by killer whales (orcas), and calves may be killed by some species of large sharks.
Calving occurs from January to March. Mothers bear a single calf, probably only every third year, and defend their calves vigorously. Newborns are about 16 feet long, and are weaned at about 9 months.
Resources:
Leatherwood, Stephen and Randall R. Reeves. 1983. The Sierra Club handbook of whales and dolphins. Sierra Club Books. San Francisco California.
