Mollusk

Mollusk

Mollusks are a large and diverse group of invertebrates, with over 85,000 recognized species. They are the second largest phylum of invertebrates, after the arthropods, and include familiar animals such as snails, clams, and squids.

Anatomy

Mollusks have a wide range of anatomical structures, but most share a few key features. These include a soft body, a muscular foot, a head with sensory organs, and a mantle that secretes a hard shell.

Soft Body

The body of a mollusk is soft and unsegmented. This allows for a great deal of flexibility and adaptability, enabling mollusks to live in a wide variety of environments.

Muscular Foot

The foot of a mollusk is a muscular organ used for locomotion. In some species, such as snails and slugs, the foot is large and flat, while in others, like clams and oysters, it is small and pointed.

Head

The head of a mollusk contains the animal's sensory organs, including eyes, tentacles, and a mouth. The head is often highly developed, especially in cephalopods like squids and octopuses, which have complex eyes and large brains.

Mantle and Shell

The mantle is a layer of tissue that covers the mollusk's body and secretes the shell. The shell is typically made of calcium carbonate and provides protection against predators and environmental hazards.

Classification

Mollusks are classified into several major groups, or classes. These include the Gastropoda (snails and slugs), Bivalvia (clams, oysters, and other bivalves), and Cephalopoda (squids, octopuses, and cuttlefish).

Ecology and Behavior

Mollusks play important roles in many ecosystems, serving as both predators and prey. They are also important in human economies, with many species harvested for food, pearls, and shells.

See Also

• Gastropoda
• Bivalvia
• Cephalopoda
• Invertebrates

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