Ocean Animals: 25 Sea Creatures From Whales to Starfish

Where do ocean animals live?

The ocean covers about 71% of Earth’s surface and has an average depth of about 3,700 m (12,100 ft), so it offers very different homes:

• Coasts and reefs: shallow, sunny water over the continental shelf, with kelp forests, seagrass meadows and coral reefs.
• The sunlit open ocean: the top 200 m (660 ft), where plankton, tuna, sharks and whales feed.
• The twilight zone: about 200–1,000 m (660–3,300 ft), where light fades and many animals glow.
• The deep sea: below 1,000 m (3,300 ft), cold and completely dark, home to strange creatures described in deep-sea animals.
• Polar seas: icy waters around the Arctic and Antarctica, rich in krill and fish in summer.

Marine mammals

1. Blue whale

The blue whale is the largest animal known to have ever lived, reaching about 30 m (98 ft) and up to around 190–200 tonnes. It lives in every ocean except the Arctic and feeds almost entirely on krill, tiny shrimp-like animals, which it gulps in huge mouthfuls. Whaling killed hundreds of thousands, and it is still Endangered.

2. Humpback whale

Humpbacks migrate up to about 8,000 km (5,000 mi) between cold feeding grounds near the poles and warm tropical waters where they breed. Males sing complex songs that last from about 4 to 33 minutes and change from year to year. Once heavily hunted, humpbacks have recovered and are now Least Concern.

3. Sperm whale

The sperm whale is the largest toothed predator on Earth and has the biggest brain of any animal, more than five times heavier than a human’s. It dives deeper than 1,000 m (3,300 ft), and sometimes beyond 2,000 m (6,600 ft), to hunt squid in the dark. It is Vulnerable.

4. Orca

The orca, or killer whale, is actually the largest member of the dolphin family. It lives in every ocean, most commonly in cold coastal waters, in family groups called pods. Different populations specialize in different prey, from fish to seals, and pass on their hunting methods. The IUCN lists it as Data Deficient.

5. Bottlenose dolphin

Common bottlenose dolphins live in warm and temperate seas worldwide, both along coasts and offshore. Each dolphin develops its own “signature whistle”, which works much like a name that others can copy to call it. They are Least Concern.

6. Sea otter

Sea otters live along the coasts of the North Pacific, from Japan and Russia to Alaska and California. Instead of blubber, they rely on the densest fur of any animal to stay warm. They use stones to crack open shellfish and help protect kelp forests by eating the sea urchins that graze on them. They are Endangered.

7. West Indian manatee

Manatees graze on seagrass in warm, shallow coasts and rivers from Florida and the Caribbean to northeastern South America. These gentle “sea cows” can weigh more than 500 kg (1,100 lb) and need warm water to survive cold snaps. They are Vulnerable, and boat strikes are a major threat.

Sharks, rays and fish

8. Whale shark

The whale shark is the largest fish in the world, reliably recorded at up to 18.8 m (61.7 ft). Despite its size, it is a gentle filter feeder that sieves plankton and small fish from warm tropical seas. It is Endangered.

9. Great white shark

Great white sharks live mainly in cool coastal waters worldwide, but some cross entire ocean basins: one tagged female swam from South Africa to Australia and back within about nine months. They can grow to about 6 m (20 ft) and are Vulnerable.

10. Giant manta ray

The giant oceanic manta ray is the largest ray, with a “wingspan” of up to about 7 m (23 ft). It glides through tropical and subtropical seas, filtering plankton, and visits reef “cleaning stations” where small fish pick parasites off its skin. It is Endangered.

11. Ocean sunfish

The ocean sunfish, or mola, is a huge, flattened fish that usually weighs 250–1,000 kg (550–2,200 lb). It is often seen lying on its side at the surface in temperate and tropical seas. A female can release up to 300 million eggs at once, more than any other known vertebrate. It is Vulnerable.

12. Atlantic bluefin tuna

This powerful predator crosses the Atlantic and can keep its muscles warmer than the surrounding water, which helps it hunt in cold seas. The heaviest on record, caught off Nova Scotia in 1979, weighed 679 kg (1,496 lb). After decades of overfishing, stricter quotas helped it recover, and it is now listed as Least Concern.

13. Ocellaris clownfish

The orange-and-white clownfish lives among the stinging tentacles of sea anemones on coral reefs of the eastern Indian Ocean and western Pacific. A protective mucus keeps it from being stung. All clownfish start life as males, and the largest fish in a group becomes the breeding female.

Sea turtles

14. Green sea turtle

The green sea turtle nests on tropical and subtropical beaches around the world. Adults are the only plant-eating sea turtles, grazing on seagrass and algae. After decades of nest protection, the IUCN moved the species from Endangered to Least Concern worldwide in 2025, although some regional populations are still in trouble.

15. Leatherback sea turtle

The leatherback is the largest living turtle, usually weighing 250–700 kg (550–1,540 lb), and it has a flexible, leathery shell instead of hard plates. It feeds on jellyfish, dives deeper than 1,000 m (3,300 ft) and roams from the tropics into cold northern waters. It is Vulnerable.

Seabirds

16. Wandering albatross

The wandering albatross of the Southern Ocean has the longest wingspan of any living bird, up to about 3.7 m (12 ft). It glides for hours on ocean winds with hardly a wingbeat and comes ashore mainly to breed. Accidental capture on fishing lines makes it Vulnerable.

17. Atlantic puffin

Puffins nest in burrows on North Atlantic cliffs and islands and spend winter far out at sea. They “fly” underwater with their wings to catch small fish and can carry many at once crosswise in their colorful bills. They are Vulnerable.

18. Emperor penguin

The largest penguin lives only around Antarctica and breeds on sea ice in the middle of winter. It can dive to more than 500 m (1,640 ft) and stay under for about 20 minutes. It is Near Threatened because climate change is shrinking the sea ice it needs.

Octopuses and squid

19. Giant Pacific octopus

The largest octopus lives in the cold North Pacific, from California to Japan. Adults usually weigh around 15 kg (33 lb), with an arm span of up to 4.3 m (14 ft). Like all octopuses, it has three hearts and blue blood, and it is famous for solving puzzles in aquariums.

20. Giant squid

The giant squid lives in the deep ocean worldwide and has the largest eyes of any living animal except perhaps the colossal squid, at least 27 cm (11 in) across. It was first photographed alive in its natural habitat only in 2004, off Japan. Sperm whales are its main predator.

Jellyfish and their relatives

21. Moon jellyfish

The moon jellyfish is common in coastal waters around the world. Its clear bell is usually 25–40 cm (10–16 in) across, and four horseshoe-shaped rings, its reproductive organs, show through the top. Its sting is weak, and it catches plankton with short tentacles and sticky mucus.

22. Portuguese man o’ war

Despite its looks, the Portuguese man o’ war is not a true jellyfish but a siphonophore, a colony of many specialized units that work as one animal. A gas-filled float carries it across warm seas, while its stinging tentacles, often around 10 m (33 ft) long, trail below. Its sting is very painful, even from animals washed up on the beach, so it should never be touched.

Sea stars, crabs and corals

23. Ochre sea star

The ochre sea star, orange or purple, lives on rocky shores of North America’s Pacific coast. Experiments in the 1960s showed that removing it lets mussels take over the shore, making it the original “keystone species”. Since 2013 a wasting disease has killed huge numbers of sea stars along the coast.

24. Japanese spider crab

The Japanese spider crab has the largest leg span of any arthropod, up to about 3.7 m (12 ft) from claw to claw, and can weigh 19 kg (42 lb). It lives on the seabed around Japan, usually between about 50 and 600 m (160–2,000 ft) deep.

25. Staghorn coral

Staghorn coral forms branching, antler-shaped colonies on reefs in Florida, the Bahamas and the Caribbean. Each colony is made of tiny animals called polyps, which share their bodies with algae that make food from sunlight. Disease and bleaching have wiped out more than 95% of its cover in some areas since the late 1970s, and it is Critically Endangered.

Ocean giants and record holders

The ocean holds most of the animal kingdom’s size records, from the blue whale to the Japanese spider crab, because water supports heavy bodies. For more, see the largest animals in the world. The biggest fish, the whale shark, and the largest whale both feed on some of the smallest animals in the sea, plankton and krill.