Concept in Definition ABC

The concept of mollusks designates that phylum or group of invertebrate animals, which lack a column vertebral, and characterized by having a soft non-segmented body, a bag that contains the viscera and a foot.

The body of mollusks is divided mainly into three parts: the head, the feet that serve to move, and the highly developed dorsal visceral mass that is enveloped by a mantle. This consists of a complex membrane that secretes a shell mineral which has the function of protecting the animal in question.

Regarding its foot we must say that in the most primitive mollusks it was a foot that crawled, with time and the corresponding evolution it diversified to the point of becoming a digger foot, a swimmer and even divided into various tentacles.

They can be presented in a naked way, as in the case of octopuses or be covered by a hard surface, such as shells, in the case of oysters, other recognized mollusks.

Metazoans, multicellular and heterotrophs

Mollusks are framed within the kingdom of the metazoans because they are

organisms multicellular, that is, its body is made up of a multiplicity of cells; its nutrition it is heterotrophic, being able to make its own organic substance and it feeds on organic matter made by other living beings.

His nervous system It is ganglionic and presents the complete digestive tract. For his part, circulatory system is composed of the heart located on the back, an aorta and vessels. The way in which they breathe is branchial and in some types they can have a simile lung.

They are normally oviparous, that is, the female lays eggs developing the embryo outside of the mother's body. There are also hermaphroditic species within mollusks and sexual differentiation is common.

Thanks to the various physiological characteristics that they display and that we have specified above, mollusks can live in a diversity of environments without problems. For example, then, it is possible to find mollusks at more than three thousand meters from sea level and also in the deepest waters of the ocean.

The term is also applied to refer to everything relative or proper to mollusks.

Photos: iStock - para827 / delectus

Topics in Mollusks