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 a group of animals with soft bodies, and many have a hard shell for protection. They’re invertebrates, meaning they don’t have backbones—so they’re distinct from vertebrates like fishes, birds, or mammals. The image of a snail or clam captures the idea, though some mollusks, such as octopuses and slugs, don’t have an external shell. They’re not plants. So the description “soft-bodied invertebrate animal, often with a hard shell” best describes mollusks.