SeaWorld Education: Life Under The Sea!

All of the animals and plants that live in the sea are a part of the ocean food chain. There are some sea creatures that eat plants, others eat animals, and some eat both! The following looks at the role of various animals and plants in the ocean food chain. Also, learn about the individual characteristics of some of the animals and plants that make their home in the ocean!

The Ocean Food Chain

Every living thing in the ocean must eat something in order to survive. Though an ocean plant such as phytoplankton doesn’t ‘eat’ anything, it needs the sun and various vitamins in order to grow. A diagram of the ocean food chain shows what various marine animals eat to stay alive. Depending on where an animal is on the food chain, it may be eaten by many other animals in the ocean. For instance, krill are tiny crustaceans that live in the ocean. They look a lot like shrimp! Krill are low on the ocean food chain which means that they are eaten by many other sea creatures including whales, squid, fish, and birds. Alternatively, sharks are high on the ocean food chain. Consequently, there are very few creatures in the ocean that eat them. On the other hand, sharks eat many animals that are below them on the ocean food chain including many types of fish, squid, and sometimes even dolphins. Not surprisingly, different types of sharks eat different types of meals! Whether an animal is high or low on the food chain, it plays an important part in the ocean’s ecosystem.

Marine Mammals

Whales, dolphins, and porpoises are just a few examples of marine mammals. Marine mammals have live babies (instead of eggs) and feed them with their own milk. Also, they are warm-blooded. Marine mammals are a lot like mammals that live on land, but they have their babies in the ocean and care for them there.

  • All about Whales: Discover information about blue whales, grey whales, humpback whales and others.
  • Facts about Seals!: Learn facts about Leopard seals, Crab eater seals and more!
  • The Lives of Dolphins: How many species of dolphins are there? Find the answer to this question and many others on this page.


Fish are vertebrates meaning that they have a backbone. They are cold-blooded and can breathe underwater through their gills. There are over 20,000 species of fish! The largest fish in the world is the whale shark. A whale shark can grow to fifty feet in length. One of the smallest fish in the world is the goby. A goby grows to about half an inch in length!


A crustacean has a shell. Lobsters, crabs, shrimp, and crayfish are all examples of crustaceans. These sea creatures eat a variety of things. For example, lobsters eat small fish, mussels and clams that they hunt for at night. Crabs also eat fish, mussels, and clams. They have also been known to eat other crabs!

  • Crab Facts: Find a description of an ocean crab and learn about some of its habits.
  • Learning about Lobsters: Check out information on what lobsters eat, where they live, and more!
  • Diagram of a Shrimp: Learn about the parts of a shrimp.
  • New England Sea Life: Find information on turtles, crustaceans, fish, marine mammals, and other sea creatures that live in the New England area.


Phytoplankton is one of the most important plants at the bottom of the ocean food chain. Phytoplankton, or floating algae, is eaten by tiny ocean creatures called zooplankton. Zooplankton is eaten by lobsters, crabs, and many types of fish. A variety of sharks eat fish, crabs, and other crustaceans. In turn, whales and other large marine mammals eat fish, and squid along with various other sea creatures. In short, if there were no phytoplankton, or other ocean plants such as seaweed, there would be an important link missing from the ocean food chain! As a consequence, the sea creatures further up the food chain (crabs, sharks, whales, etc.) would have very little to eat. Each living thing in the ocean depends on another for its survival.

  • Undersea Plant Life: Find out some facts about undersea plants such as kelp and phytoplankton.
  • All about Seaweed: Discover what seaweed is as well as some of its characteristics.

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