Marine Mammals

Marine mammal conservation is not about saving one uniform group with one conservation status. Whales, dolphins, porpoises, seals, sea lions, manatees, dugongs, and sea otters include species and populations with very different trends. Some have recovered substantially from past exploitation, while others remain at serious risk from fishing gear, vessel strikes, habitat change, underwater noise, … Read more

Marine mammal migration is the repeated movement of animals between areas that offer different seasonal advantages. A whale may leave a productive feeding ground for a warmer breeding area. A seal may spend months foraging at sea before returning to a traditional breeding colony. Arctic whales may follow shifting sea ice and openings in the … Read more

Marine mammals communicate underwater mainly through sound because sound can travel efficiently through water even when visibility is poor. Whales use calls and, in some species, songs. Dolphins and other toothed whales use whistles, burst-pulsed sounds, and clicks. Pinnipeds such as seals and sea lions can vocalize both underwater and in air, while sirenians and … Read more

Marine mammals do sleep, but they do not all solve the problem in the same way. Dolphins and other cetaceans can show unihemispheric slow-wave sleep, in which one cerebral hemisphere displays sleep-like slow waves while the other remains in a more wake-like state. Some eared seals can also use this pattern in water, yet switch … Read more

Marine mammals stay warm in cold water by controlling how quickly heat leaves the body and by producing enough metabolic heat to replace what is lost. Most whales and many seals rely heavily on blubber, sea otters depend much more on exceptionally dense fur, and many species use blood-vessel arrangements that conserve heat in flippers, … Read more

Marine mammals can spend remarkable amounts of time underwater, but they do not breathe there. Whales, dolphins, seals, sea lions, manatees, dugongs, and sea otters all use lungs and must return to the surface for air. Their diving ability comes from managing a limited oxygen supply efficiently, not from extracting oxygen from seawater. The most … Read more

Manatees and dugongs are close relatives, but they are not the same animal. The easiest difference to see is the tail: manatees have a broad, rounded, paddle-shaped tail, while dugongs have a two-lobed fluked tail that looks more like the tail of a whale or dolphin. Their faces, teeth, geographic ranges, preferred habitats, and feeding … Read more

Seals and sea lions are both pinnipeds, but they are not the same kind of animal. The quickest clue is usually the ears: sea lions have visible external ear flaps, while true seals have ear openings without an outer flap. Their flippers and movement provide an even stronger comparison. Sea lions can rotate their hind … Read more

Whales, dolphins, and porpoises are all cetaceans, but those everyday names do not divide the group into three simple, equal taxonomic categories. Dolphins and porpoises are both toothed cetaceans, while animals commonly called whales include both baleen whales and several toothed cetaceans. That is why an orca can be called a killer whale and still … Read more

Whales, seals, manatees, and sea otters can all be called marine mammals, but that does not mean they belong to one close branch of the mammal family tree. They are mammals from different evolutionary lineages that became dependent on aquatic environments in different ways. Some, such as whales and dolphins, spend their entire lives in … Read more