What Lives in Water & Has a Shell?

There are many species of animals that live in the water and have shells. Many of these animals, such as clams, mussels and oysters, are members of the Mullosk family. Many types of shelled underwater animals are eaten by cultures all across the world. Some shelled aquatic animals live in the ocean and others live in fresh water. Many live in both.

  1. Giant Clam

    • Giant clams can weigh more than 400 pounds.

      The giant clam, or Tridacna gigas, is an invertebrate animal native to Pacific and Indian Oceans. It is a relative of the common clam, but grows much larger, reaching up to four feet in length and weighing more than 400 pounds. Giant clams are bottom dwelling animals that fasten themselves to underwater rocks or reefs and remain in the same spot for their entire lives. They are the largest mollusks in the world. Giant clams feed on the sugars produced by algae that live in their tissue. The clam's adductor muscle, which is used to open and close its enormous shell, is considered a delicacy in parts of southeast Asia.

    Geographic Cone Snail

    • The geographic cone snail, or Conus geographus, is a species of marine snail that is native to the reefs of the Indo-Pacific. These snails grow to be about six inches long and have intricately patterned white and brown shells that are prized by shell collectors around the world. The geographic cone snail is highly venomous and uses its venom to instantly paralyze its prey. This venom is injected into the prey by a harpoon-like tooth. This snail is so poisonous that it's nickname is the "cigarette snail"; locals of the region claim that if a person is stung by one, he will only have time to smoke a cigarette before he dies.

    Oyster

    • Many people enjoy eating raw oysters.

      The oyster, or Ostreidae, is an invertebrate native to oceans in most parts of the world. Oysters are usually found in large colonies called beds or reefs, which are located in shallow waters. True oysters are not from the same bivalve family as pearl-producing oysters, though true oysters can produce pearls as well. They have rock-hard shells that are difficult to pry open due to their strong adductor muscles. They use these muscles to close their shells when threatened. Oyster shells are usually pear-shaped or oval and are whitish-gray on the outside and pearl-white on the inside. These invertebrates are eaten all across the world. Oyster meat is high in iron, calcium and protein.

    Mussels

    • Mussels are often served in their shells.

      Mussels are mollusks native to waters all around the world. They can be found in the ocean or in fresh water, such as lakes and streams. Mussels are closely related to clams. Like clams, they have a soft body that is protected by a hard outer shell. When the mussel senses a threat, it closes the two parts of its shell together using its adductor muscle. Mussels play an important role in marine and freshwater ecosystems, as they help clean the water by filtering oxygen and partictles out of it.