Molluscos

Molluscos is a phylum of invertebrate animals. This phylum is one of the largest and most diverse, encompassing over 100,000 known species. Molluscs are found in all of the world's oceans, freshwater environments, and on land. They exhibit a wide range of forms and lifestyles, from microscopic sea slugs to large squid and octopuses.

The phylum Mollusca is characterized by a few key features, although not all are present in every species. Many molluscs possess a soft body, often protected by a shell made of calcium carbonate. This shell can be external, like in snails and clams, or internal, as in squid. A common feature is a muscular foot, used for locomotion, burrowing, or attachment. They also typically have a mantle, a fold of tissue that secretes the shell and encloses the visceral mass, which contains the organs. Many molluscs have a radula, a ribbon-like structure with teeth, used for scraping food. Respiration usually occurs through gills, although terrestrial species may have a lung-like structure.

The diversity within Mollusca is immense. Major classes include Gastropoda (snails and slugs), Bivalvia (clams, oysters, mussels), Cephalopoda (squid, octopus, cuttlefish), and Polyplacophora (chitons). These animals play vital roles in various ecosystems, serving as prey for other animals, as filter feeders influencing water quality, and as important food sources for humans. Their shells have also been historically used for trade and adornment.