A mollusc, or mollusk, is a diverse and intriguing phylum of invertebrate animals belonging to the kingdom Animalia. This phylum comprises a vast array of organisms with distinct characteristics, including a soft, unsegmented body and, in most cases, a protective external or internal shell. Molluscs exhibit remarkable diversity in terms of size, shape, habitat, and ecological role.
Key features of molluscs include a muscular foot that they use for movement, a mantle—an outer tissue layer that often secretes a shell—and a radula, a specialized feeding organ equipped with tiny teeth. The radula is used for various feeding techniques, from grazing on algae to drilling into shells for predation. Molluscs have a well-developed circulatory system and a simple nervous system.
The phylum Mollusca encompasses a wide range of species, including gastropods (snails and slugs), bivalves (clams, mussels, and oysters), cephalopods (octopuses, squids, and cuttlefish), and more.
These organisms inhabit diverse environments, from marine and freshwater habitats to terrestrial ecosystems. Some molluscs are adapted to live in extreme conditions like hydrothermal vents in the deep ocean.
Molluscs hold ecological significance as important members of marine and aquatic food chains. They serve as prey for various organisms and also contribute to ecosystem processes such as nutrient cycling. Economically, molluscs have cultural and culinary importance. Many bivalve molluscs are consumed as seafood, while their shells are used in jewelry and crafts.
From an evolutionary standpoint, molluscs are of great interest to biologists studying phylogenetics and developmental biology. The phylum’s diverse forms and characteristics provide insights into evolutionary processes, adaptation to different habitats, and the relationship between form and function.