What is a mollusk?

What is a mollusk?

• A. A vertebrate with a backbone.
• B. A soft-bodied invertebrate animal, often with a hard shell.
• C. A type of fish.
• D. A plant.

Answer: (B)

Mollusks are animals that belong to a group characterized by soft bodies and, in many species, a shell. They are invertebrates, meaning they don’t have a backbone. A typical mollusk has a mantle that can secrete a calcium-containing shell, a muscular foot used for movement, and a visceral mass containing its organs; many also have a feeding structure called a radula. Some mollusks, like snails and clams, have visible shells, while others, such as octopuses and squids, either lack an external shell or have only a small internal one. This combination of soft body plan, lack of backbone, and shell-producing mantle distinguishes mollusks from vertebrates like fish and from plants. Examples include snails, clams, oysters, and octopuses.

Mollusks are animals that belong to a group characterized by soft bodies and, in many species, a shell. They are invertebrates, meaning they don’t have a backbone. A typical mollusk has a mantle that can secrete a calcium-containing shell, a muscular foot used for movement, and a visceral mass containing its organs; many also have a feeding structure called a radula. Some mollusks, like snails and clams, have visible shells, while others, such as octopuses and squids, either lack an external shell or have only a small internal one. This combination of soft body plan, lack of backbone, and shell-producing mantle distinguishes mollusks from vertebrates like fish and from plants. Examples include snails, clams, oysters, and octopuses.