Friday, October 8, 2010

Enhydra Lutris

General range: Coast of Russia, western Canada, and the United States.
Range in Washington: Reintroduced along coast.
Habitat: Kelp beds in ocean.
Diet: Sea urchins, shellfish.
Habits: Exclusively aquatic; uses rocks as tools to crush shells.
Identification: Dark brown with yellowish head; large crushing molars. Total length: 75-180 cm; tail: 25-35 cm; mass: 12-36 kg. Males larger than females.
Conservation: State Endangered

Sea otters are marine mammals. They inhabit temperate coastal waters with rocky or soft sediment ocean bottoms less than 1 km from shore. Kelp forest ecosystems are characteristic of otter habitats.

Physical Description:
Mass14 to 45 kg; avg. 29.50 kg(30.8 to 99 lbs; avg. 64.9 lbs)
Length1 to 1.50 m; avg. 1.25 m(3.28 to 4.92 ft; avg. 4.1 ft)
Sea otters are the largest member of the family Mustelidae. Males weigh 22 to 45 kg and are 1.2 to 1.5 m in length. Females are slightly smaller, weighing 14 to 33 kg and measuring 1 to 1.4 m in length. The tail comprises less than a third of the body length. The pelage is brown or reddish brown. Sea otter fur is the densest of all mammals, with about 100,000 hairs per square centimeter. Since sea otters do not have any insulating fat, the fur is responsible for maintaining warmth. The hind legs are long and the paws are broad, flat, and webbed. The forelimbs are short and have retractable claws. Sea otters are the only carnivorans with just 4 lower incisors. Females have two mammae.

Sea otters are solitary for the most part. Males congregate in groups when resting. Females tend to stay away from males except when mating. Sea otters can spend their whole life in the ocean but will rest on land when the population density is high. Swimming is performed using the hind limbs, tail, and vertical undulations of the body while the forelimbs are tucked into the chest. Otters can swim as fast as 9 km per hour under water. Sea otters are diurnal with crepuscular peaks in foraging activity. Foraging dives usually last 50-90 seconds, but otters can remain submerged for nearly 6 minutes. Foraging takes up 15-55% of an otter's time; time is dependent on availability of food. Prey is located using vision and touch and is captured with the forepaws. It is then brought to the surface where feeding takes place as the otter floats on its back using its chest as a table. Sea otters are one of few mammals that exhibit tool use. Prey items with hard shells or exoskeletons are broken open with a rock. Some otters will hold the rock on their chests and drive the prey into the rocks. Others will leave the prey on their chests and hit the prey with the rocks. The same rock is kept for many dives. Otters will often wash their prey by holding it against their body and turning in the water. Males steal from females if they get a chance. For this reason, females tend to forage in separate areas. When resting or sleeping, sea otters float on their backs and wrap themselves in kelp to keep from drifting. Their hind limbs stick up out of the water and forelimbs are either folded on their chest or used to cover their eyes. Grooming and cleaning their fur is important for maintaining its insulating ability.

No comments:

Post a Comment