Mollusks Anatomy

Many mollusks have a hard external shell but others do not. The eyes of the giant squid are the largest in the animal kingdom almost the size of dinner plates.

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The morphology and anatomy of modern bivalves have been much altered from those of ancestral mollusks which had a distinct anterior end with a mouth and a posterior end with an anus figure 1.

Mollusks anatomy. Although basically marine bivalves and gastropods include freshwater species. Locomotion the foot is the organ of locomotion in land gastropods. Many mollusks have a hard external shell but others do not.

Gastropods have also adapted to land with thousands of species living a fully terrestrial existence. External features pair of lamellate gills ctenidia a thick layer of glandular epithelium called mucus tracts or hypobranchial glands and the outlets for the digestive excretory and reproductive systems. There are over 50000 different types of mollusks alive today.

Genital gland producing spermatozoa sperm or ova eggs depending on the sex of the mollusk. Radula plural radulae or radulas horny ribbonlike structure found in the mouths of all mollusks except the bivalves. As such their circulatory systems are mainly open.

The coelom is a cavity present in body of molluscs which contains internal organs suspended from mesenteries. The foot although the basic form of the foot is a flat broadly tapered muscular organ which is highly. The main body cavity is a hemocoel through which blood circulates.

Mollusks are a phylum of soft bodied invertebrate animals. The mollusks have adapted to all habitats except air. The anatomystructures of molluscs are complex in nature.

Let us find out more information about the anatomical characteristics of molluscs. Gills respiratory organs located between the foot and the mantle formed of two layers of ciliated filaments which filter water and retain food particles. Most molluscs have a head with eyes and all have a pair of tentacles with sensors also on the head that detect chemicals vibrations and touch.

One of the special features of their body structure is the presence of a coelom. Although molluscs are coelomates the coelom tends to be small. In swimming and sessile forms however the foot is greatly reduced or greatly modified.

Only some species of molluscs have a brain. The radula part of the odontophore may be protruded and it is used in drilling holes in prey or in rasping food particles from a surface.

Molluscs Of Australia