molluska

Molluska, commonly known as mollusks, represent a diverse and large phylum of invertebrate animals known as Mollusca. They inhabit a wide range of environments, from deep oceans to freshwater and terrestrial habitats. The phylum is characterized by a soft, unsegmented body that is usually divided into three main parts: the head-foot, visceral mass, and mantle. Many mollusks possess a calcareous shell that provides protection, although this feature is reduced or lost in some groups.

Mollusks exhibit a variety of forms, including snails, slugs, clams, oysters, cephalopods like octopuses and squids, and others. They display complex behaviors and a range of feeding strategies, from grazing on algae to predation. The movement is often facilitated by a muscular foot, which varies significantly among different classes.

Reproduction in mollusks can be sexual or, in some cases, hermaphroditic. Most species have a larval stage called a trocophore, which contributes to their widespread distribution. Their circulatory system is typically open, although cephalopods have a closed circulatory system for more efficient oxygen transport.

Mollusks play important ecological roles as grazers, prey, and filter feeders, and they are also economically significant for their shells, pearls, and as seafood. The diversity of the molluskan phylum makes it one of the most successful groups of invertebrates, with over 85,000 recognized species and many more yet to be described.

Despite their success, mollusks face threats from habitat destruction, pollution, and overharvesting, highlighting the importance of conservation efforts for maintaining their populations and ecological functions.