How many aquatic mammals are there

Many marine mammal species can stay underwater for a long time, but must come to the surface to breathe. To be able to stay underwater for long periods, they store extra oxygen in their muscles and blood. They also have more blood than land mammals in proportion to their body sizes, can direct their blood flow to only their vital organs such as their heart and lungs , and can slow their heartbeat down so they are using less oxygen in a dive.

The Marine Mammal Center has worked extensively with species that are considered to be endangered or threatened, such as the southern sea otter, Hawaiian monk seal and Guadalupe fur seal. Threatened and endangered species are species that are at risk of extinction.

In addition, all marine mammals are protected in the United States by the Marine Mammal Protection Act , which makes it illegal to harass, feed, hunt, capture or kill any marine mammal. As a nonprofit funded by people like you, The Marine Mammal Center has special permits from the federal government that allow us to respond to stranded marine mammals.

These laws, as well as other international laws and treaties protecting marine mammals, play a critical role in the survival of marine mammals and the health of our ocean ecosystem. You can help support the care of marine mammal patients at The Marine Mammal Center with a symbolic adoption today.

Choose from a wide variety of species cared for at our hospital, including elephant seal pup Bilbo. Close Notification Close icon.

Will You Be Yura's Hero? Learn About Marine Mammals. California sea lion Northern elephant seal Pacific harbor seal Northern fur seal Guadalupe fur seal Hawaiian monk seal Steller sea lion Humpback whale Gray whale Blue whale Harbor porpoise Common bottlenose dolphin Vaquita Pacific white-sided dolphin Southern sea otter.

Found along the coasts and estuaries of Florida, Central America and the West Indies, the massive, slow-moving North American manatee is one of three species of manatee. It grows up to 13 feet long and weighs up to 1, pounds. Its diet is composed of water grasses, weeds and algae, and it eats as much as one-tenth of their body weight every day. The average life span in the wild is up to 40 years. Dugongs grow up to 10 feet long and weigh to 1, pounds. They are closely related to manatees, and they never leave the water.

Unlike the manatee they have a hairless body and a fluked horizontal tail like a whale's. They can stay underwater for up to six minutes. Frequenting the warm coastal waters of the western Pacific, Indian Ocean and Red Sea, dugongs are often observed alone or in pairs, and sometimes in herds of more than Dugongs root for water grasses day and night.

Docile dugongs are long-lived in the wild, with an average life span up to 70 years. The hippopotamus loves water and stays submerged up to 16 hours of the day. With its eyes and nostrils set high up on its head, it is often tall enough to stay submerged and breathe at the same time.

Hippopotami leave the water at dusk to feed on land vegetation. Found only in rivers in Africa, hippopotami are between 10 and 15 feet long including the tail. They weigh 5, to 8, pounds and live an average of 40 years in the wild.

Semiaquatic river otters, like other amphibious mammals, have dense, thick fur and streamlined bodies designed for life in the water. There are several species; the North American river otter lives along rivers, lakes and large creeks. River otters weigh up to 18 pounds and reach up to 4 feet long, including their tail.

Sea otters are the largest member of weasel family, and the only one that lives almost entirely in the water -- hunting on the ocean floor, and coming to the surface to eat, groom, rest and socialize with other otters. The average adult grows up to 5 feet long and weighs up to 70 pounds -- females are slightly smaller.

Populations throughout southeast Alaska, British Columbia and Washington are stable and increasing, while the numbers of sea otters in southwest Alaska are declining mainly because of predation by the killer whale. Sea otters can live up to 25 years in the wild.

Primarily aquatic, beavers are found in rivers and lakes in Europe, Asia and throughout North America, except northern Canada, the southern deserts of the United States and Mexico. They have a waterproof coat, closable ears, closable nostrils, paddle-shaped tail and webbed feet. These to pound rodents can greatly change whole environments with their dam-building activities. Introduced intentionally and accidentally to North America, the nutria or coypus is native to Central and South America.

It weighs up to 25 pounds. Well adapted to a semiaquatic life, nutria have small eyes and ears, and large, webbed hind feet for swimming. Muskrats are good swimmers and can stay underwater up to 17 minutes, preferring to live in 4 to 6 feet of water. Found in swamps, marshes, and wetlands from northern North America to the Gulf coast and the Mexican border, they are about 2 feet long and up to 4 pounds.

The duck-billed platypus lives in the freshwater rivers and streams of eastern Australia, Tasmania and New Guinea. It lays eggs and has a long, leathery bill equipped with electroreceptors that help detect the magnetic fields of the aquatic invertebrates it feeds upon. Platypus are up to 2 feet long and 4 pounds. Their average life span in the wild is up to 17 years. Based in Ontario, Susan Dorling has written professionally since , with hundreds of articles published in a variety of popular online venues.

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