Which characteristic is typical of crustaceans?

Which characteristic is typical of crustaceans?

• A. They are vertebrates with backbones.
• B. They lack a protective covering.
• C. They have a hard exoskeleton.
• D. They live exclusively on land.

Answer: (C)

Crustaceans are characterized by having a hard exoskeleton. This external shell, made of chitin and often mineralized, protects the animal and provides surfaces for muscle attachment. Because the shell is rigid, crustaceans must molt it as they grow. They are invertebrates, not vertebrates, so they don’t have backbones. The exoskeleton also helps minimize water loss in their often aquatic environments. While some crustaceans spend time on land, many live in water, so living exclusively on land isn’t typical for the group.

Crustaceans are characterized by having a hard exoskeleton. This external shell, made of chitin and often mineralized, protects the animal and provides surfaces for muscle attachment. Because the shell is rigid, crustaceans must molt it as they grow. They are invertebrates, not vertebrates, so they don’t have backbones. The exoskeleton also helps minimize water loss in their often aquatic environments. While some crustaceans spend time on land, many live in water, so living exclusively on land isn’t typical for the group.