Related topics: whales · gulf of mexico · plos one · species · dolphins

Pacific killer whales are dying—new research shows why

Killer whales are icons of the northeastern Pacific Ocean. They are intimately associated with the region's natural history and First Nations communities. They are apex predators, with females living as long as 100 years ...

Researchers find consistent mercury levels in arctic seals

Ringed seals and other Arctic marine mammals are important in the diet of Arctic Indigenous peoples. A study spanning 45 years of testing indicates that mercury concentrations in ringed seals from the Canadian Arctic have ...

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Marine mammal

Marine mammals are a diverse group of roughly 120 species of mammal that are primarily ocean-dwelling or depend on the ocean for food. They include the cetaceans (whales, dolphins, and porpoises), the sirenians (manatees and dugong), the pinnipeds (true seals, eared seals and walrus), and several otters (the sea otter and marine otter). The polar bear, while not aquatic, is also usually considered a marine mammal because it lives on sea ice for most or all of the year.

Marine mammals evolved from land dwelling ancestors and share several adaptive features for life at sea such as generally large size, hydrodynamic body shapes, modified appendages and various thermoregulatory adaptations. Different species are, however, adapted to marine life to varying degrees. The most fully adapted are the cetaceans and the sirenians, which cannot live on land.

Despite the fact that marine mammals are highly recognizable charismatic megafauna, many populations are vulnerable or endangered due to a history of commercial exploitation for blubber, meat, ivory and fur. Most species are currently protected from commercial exploitation.

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