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

New research reveals sound of deep-water animal migration

New research finds there is a distinct sound coming from a massive community of fish, shrimp, jellies and squid as they travel up and down from the depths of the ocean to the water's surface to feed. This sound could be serving ...

Smithsonian scientists solve 'sudden death at sea' mystery

Mass strandings of whales have puzzled people since Aristotle. Modern-day strandings can be investigated and their causes, often human-related, identified. Events that happened millions of years ago, however, are far harder ...

The worrying state of Mediterranean fish stocks

Fish stocks in the Mediterranean Sea are deteriorating at an alarming rate. A recent analysis by the European Commission's Joint Research Centre (JRC) shows that 93% of the assessed fish stocks are overexploited, and a number ...

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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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