Mollusks invertebrates, Invertebrates Animals, Fish, Reptiles, Amphibians, Birds, Mammals

Invertebrates Facts

Invertebrates are multi-cellular and all the cells have different responsibilities to keep the animal alive.

Invertebrates have no backbone or bony skeleton or cells wall like all other animals.

Invertebrates like echinoderms do not have heads.

There are millions of invertebrates living in our house in the name of dust mites which are hardly visible to human eyes.

Invertebrates under a process called metamorphosis through which they change form as they grow.

Mollusks

Mollusks are soft bodied invertebrate animals that belong to the phylum mollusca. These are the second largest phylum animals after the arthropoda. This group contains more than 70,000 species which includes snails, octopuses, squids, and clams. Most of the mollusks have an external hard shell to protect their soft skin like organs. Some species of mollusks have internal shells then external shells.

Mollusks like snail and slug habitat on land while the mollusks species like octopus, squid, clam, and mussel live in water. The land habitat mollusks move slowly with the help of a flat sole called the foot but the marine habitat mollusks move/swim with jet force.

The marine habitat mollusks have the ability to move fast since they eject water from their body cavity. But the ocean living mollusks oyster will attach him to the rock or the ocean floor and it will not move. They feed on the small food particles that float in the water and flow through them.

Mollusk is also called as shellfish. And they can be groped into three sections. They are:

Hatchet foot - the mollusks that have two shells and the shells are connected with the muscular hinge which helps the shells to open and close. The mollusks that belong to this group are called as bivalves. The age of the mollusk can be calculated with the help of lines in the shells.
Belly foot - the mollusks have one spiral shell and have their shells at the back. These are called as univalves.
Head foot - the mollusk will have a definite head that is surrounded by tentacles.

Generally the body of the mollusks is made up of three regions. The head, visceral mass, and a foot. The brain and sensory organs are found in the head region while the internal organs are found in the visceral mass. The foot is the lower muscular part of the body which has contact in the floor. For more information about the body structure of the mollusks refer to the page Anatomy of Mollusks.

Though mollusks are small species they have a well developed body organs. Their bodies are not segmented. In addition they have a tongue of sorts called as radula. For information about the characteristic of mollusks take a visit to the page Characteristics of Mollusks.

Mollusks can be classified into seven major classes. They are Monoplacophora, Polyplacophora, Aplacophora, Gastropoda, Scaphapoda, Bivalvia, and Cephalopoda. To get detailed information about the classification of mollusks take a visit to the page Classification of Mollusks.

Mollusks can either be carnivores, herbivores, filter feeders, detritus feeders, or parasites. Mollusks are also eaten by humans and by other animals. Snails, clams, scallops, mussels, oysters, squid, and octopus are the most popular mollusks foods. Snails are used for research as they are cancer free. Mollusks are indicators of environmental pollution.