Not all marine organisms have a backbone. Some, like jellyfish and sea urchins, are invertebrates.

Crustaceans, which include crabs, lobsters, and shrimp, are the largest group of marine organisms.

Lampreys are not fish, but are actually a type of jawless vertebrate.

The whale shark is the largest fish in the world, growing up to 40 feet long.

Sea lions are actually a type of pinniped, which are marine mammals that have flippers and spend most of their time in the water.

The blue whale is the largest marine mammal in the world, growing up to 100 feet long and weighing up to 200 tons.

Saltwater crocodiles are not marine reptiles, but are actually a type of crocodilian that can tolerate salt water.

The leatherback sea turtle is the largest marine reptile in the world, growing up to 6 feet long and weighing up to 2,000 pounds.

Penguins are not marine birds, but are actually a type of flightless bird that lives in the Southern Hemisphere.

The wandering albatross is the largest marine bird in the world, with a wingspan of up to 11 feet.

Coral is not a marine invertebrate, but is actually a type of colonial animal that forms hard skeletons.

The giant squid is the largest marine invertebrate in the world, growing up to 43 feet long and weighing up to 2,200 pounds.

Coral is not a marine plant, but is actually a type of colonial animal that forms hard skeletons.

Giant kelp is the largest marine plant in the world, growing up to 200 feet long.

Mangrove swamps are not a marine ecosystem, but are actually a type of coastal ecosystem that is found in tropical and subtropical regions.