Ocean Life Field Guide
Discover the Animals of the Sea
The ocean covers more than two-thirds of Earth's surface. Scientists have formally described roughly 240,000 marine species, and many researchers believe the true number is far higher, since so much of the deep sea remains unexplored. Marine animals span fish, mammals, reptiles, invertebrates, and seabirds — from microscopic zooplankton to the blue whale, the largest animal ever known to have existed.
Learn About Marine Life
Marine Species Guides
In-depth, fact-checked guides to the animals that call the ocean home.
Manatees
Gentle, herbivorous marine mammals related to elephants and hyraxes, grazing on sea grass in warm coastal waters and rivers.
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Sea Otters
The smallest marine mammal in North America, using tools to crack open shellfish and relying on the densest fur of any animal to stay warm.
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Seals
Earless pinnipeds built for speed and diving, spending most of their lives in open water and hauling out only to rest and give birth.
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Sea Lions
Eared pinnipeds known for their agility on land, loud vocal calls, and highly social colonies along rocky coastlines.
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Sea Turtles
Ancient marine reptiles that migrate thousands of miles between feeding grounds and the beaches where they were born.
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Sharks
Cartilaginous fish that have patrolled the oceans for more than 400 million years, from apex predators to filter feeders.
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Stingrays & Manta Rays
Flattened cartilaginous relatives of sharks that glide through the water on wing-like pectoral fins.
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Walruses
Massive Arctic pinnipeds recognized by their long ivory tusks, dense whiskers, and thick blubber layer.
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Dolphins
Dolphin biology, species, and behavior live on our dedicated sister site, About Dolphins.
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Whales
Whale species, migration routes, and conservation status live on our dedicated sister site, About Whales.
View Details →Where They Live
Ocean Habitats
Mangroves
Salt-tolerant trees and shrubs that grow where land meets sea, forming nursery habitat for countless coastal species.
Seagrass Meadows
Flowering plants that grow fully submerged in shallow, clear coastal waters, requiring enough sunlight to photosynthesize.
Intertidal Zone
The shoreline strip exposed at low tide and submerged at high tide, home to starfish, mussels, and sea urchins.
Open Ocean (Pelagic Zone)
Water beyond the coast, layered from the sunlit surface down to the pitch-dark depths of the deep sea.
Coral Reefs
Sometimes called the rainforests of the sea, reefs built by coral organisms host some of the highest biodiversity of any marine habitat.
Hydrothermal Vents
Deep-sea fissures releasing mineral-rich, superheated water, supporting life that survives on chemical energy instead of sunlight.
Did You Know?
Learn & Play
For Curious Young Explorers
Coloring Pages
Printable marine animal coloring sheets, free to download and color at home or in the classroom.
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Photo Gallery
Browse a gallery of marine life photography spanning every species we cover.
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Animal Sounds
Listen to real recordings of marine animal calls, from whale song to seal barks.
View Details →Marine Animal Gifts
Ocean-inspired gifts for every marine life lover — postcards, apparel, home decor, and more.