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marine animal
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Line graph showing the number of marine animal families from the Precambrian era to the present, with illustrations of key groups such as trilobites, ammonoids, marine reptiles, and diatoms. The graph highlights major extinction events and a rise to 1,900 living families today.
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marine animal

Also known as: marine fauna
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Line graph showing the number of marine animal families from the Precambrian era to the present, with illustrations of key groups such as trilobites, ammonoids, marine reptiles, and diatoms. The graph highlights major extinction events and a rise to 1,900 living families today.
marine family diversity The diversity of marine animal families since late Precambrian time. The data for the curve comprise only those families that are reliably preserved in the fossil record; the 1,900 value for living families also includes those families rarely preserved as fossils. The several pronounced dips in the curve correspond to major mass-extinction events. The most catastrophic extinction took place at the end of the Permian Period.

Marine animals are diverse organisms that live in the ocean and depend on marine environments for survival. These animals have evolved unique physiological and behavioral adaptations to thrive in seawater. For example, some Antarctic fish have antifreeze proteins in their blood to survive near-freezing temperatures. Many marine animals achieve neutral buoyancy, and some in the deep sea generate light to attract prey or avoid predators.1

Marine mammals, a specific group of marine animals, breathe air, are warm-blooded, have hair, and nurse their young with milk. They include whales, dolphins, seals, sea lions, manatees, dugongs, and sea otters. These animals are found in all the world's oceans and have adapted to marine life with streamlined bodies, insulating blubber or dense fur, and modified limbs.2

Marine biota can be categorized into plankton (drifting organisms) and nekton (active swimmers). Nekton, often the most recognizable marine animals, include fish, reptiles, mammals, mollusks, and crustaceans. They are found at all depths and are crucial components of marine food chains.3

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
4 Britannica Sources
  1. marine ecosystem - Physical and chemical properties of seawater
  2. What Is a Marine Mammal?
  3. marine ecosystem - Nekton
  4. marine ecosystem - Geography, oceanography, and topography

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