There are many different oceanic mollusks, such as clams, octopus and oysters, but there are also mollusks that live on land, such as snails and slugs. Mollusks are the second largest group of invertebrates in the world, with somewhere between 50,000 and 200,000 living species.Know More
Mollusks can be separated into a number of smaller categories, such as univalve, bivalve and cephalopods. Cephalopods are a group that contains cuttlefish, squid and octopus. Univalve mollusks are those that only have one shell, such as snails, while bivalve mollusks are those with two connecting shells. Virtually all univalves have a protective shell, which grows in a spiral pattern. The only exception is slugs, which are also considered univalve despite the fact that they have lost the ability to grow a shell through evolution.
Examples of bivalve mollusks include scallops and clams. Although snails are technically univalve, they actually belong to the group known as gastropods, which also includes both sea and land slugs, limpets, sea cucumbers and sea hares. Both univalve and bivalve mollusks are often prized for their extraordinary shells. Basically all shells that are found on beaches across the world come from some species of mollusk. Some of the most prized mollusk shells include conch, cowrie and whelk, which are all univalve gastropods.Learn more about Marine Life
Clams live in both salt water and fresh water. Most clams are found in shallow water in areas that are muddy or sandy. However, there is a particular species known as Abra profundorum, which can be found in the Pacific Ocean at depths of up to 16,000 feet.Full Answer >
Of the 15,000 species of bivalves known as clams, some have life cycles of only one year. Individuals of one species called the ocean quahog, or Arctica islandica, however, are among the oldest living animals on Earth, with one captured specimen measured to be more than 500 years of age.Full Answer >
Mollusks have bilateral symmetry, although some mollusks have lost their symmetry during development, as reported by Rutger's University. The mollusk phylum include organisms like snails, oysters, claims, octopuses and even squids. Most have a calcareous shell, whether it be internally or externally, and well-developed respiratory, digestive, excretory and circulatory systems.Full Answer >
Bivalves are mollusks that show no cephalization, according to Clinton Community College. The biological makeup of mollusks does not include a head, central nervous system and sensory organs that are needed for cephalization in higher animals, notes Estrella Mountain Community College.Full Answer >