What is a mollusc simple definition?

: any of a large phylum (Mollusca) of invertebrate animals (such as snails, clams, or squids) with a soft unsegmented body usually enclosed in a calcareous shell broadly : shellfish.

A mollusc is an invertebrate (meaning it has no backbone). Molluscs have very soft bodies and are massively diverse. Many have shells. Some live underwater, in marine and freshwater environments while others live on land.

The term Mollusca was derived from the term given by Aristotle to cuttlefish. Mollusc means soft. These organisms are found in the terrestrial as well as in deep seas. Their size ranges from microscopic organisms to organisms 20 metres long.

The literal meaning of Mollusca is Soft-bodied animals. It comprises the second largest phylum of Animalia. Molluscs are terrestrial or aquatic(marine or freshwater).

Classification

The molluscs include many familiar animals, including Clams, snails, slugs, and squid, as well as some less familiar animals, like tusk shells and chitons (Fig. 3.51 A). Molluscs are found in nearly all freshwater and marine environments, and some are found also on land.

Mollusks are Invertebrates such as snails, scallops, and squids. Mollusks have a hard outer shell. There is a layer of tissue called the mantle between the shell and the body. Most mollusks have tentacles for feeding and sensing, and many have a muscular foot.

Characteristic Features of Phylum Mollusca

• They are bilaterally symmetrical.
• They are triploblastic, which three layers.
• They show organ system grade of organisation.
• The body is soft and unsegmented.
• Body is divisible into three regions – head, a visceral mass, and ventral foot.
• Body is covered by a mantle and shell.

Molluscs are A clade of organisms that all have soft bodies which typically have a “head” and a “foot” region. Often their bodies are covered by a hard exoskeleton, as in the shells of snails and clams or the plates of chitons.

The bivalves (meaning “two-shells”) are perhaps the most well known mollusks simply because of their history as a source of food. Clams, mussels, oysters and scallops are all bivalves. There are about 15,000 known species of bivalve, with about 80% of them being marine (the rest are found in fresh water).

Examples

• Clams.
• Mussels.
• Octopus.
• Pila ( Snail)
• Oyster.
• Cuttlefish.
• Squid.

Mollusks are important in a variety of ways; they are used As food, for decoration, in jewelry, and in scientific studies. They are even used as roadbed material and in vitamin supplements.