Crustaceans are defined as what?

Crustaceans are defined as what?

• A. Mammals with fur that live in water.
• B. Birds adapted to water for flight.
• C. They have a hard exoskeleton.
• D. A group of aquatic animals with a hard exoskeleton, such as crabs and shrimp.

Answer: (D)

Crustaceans are a group of aquatic arthropods that have a hard external shell, or exoskeleton, covering their bodies. This shell provides protection and support while their jointed limbs enable many different movements. The best description among the options is the one that specifies a group of aquatic animals with a hard exoskeleton, such as crabs and shrimp, because it captures both the living habitat and the protective outer covering that define crustaceans. The other choices describe mammals or birds, which are not crustaceans, and noting only a hard exoskeleton is too vague without mentioning the aquatic lifestyle and the broader arthropod relationship.

Crustaceans are a group of aquatic arthropods that have a hard external shell, or exoskeleton, covering their bodies. This shell provides protection and support while their jointed limbs enable many different movements. The best description among the options is the one that specifies a group of aquatic animals with a hard exoskeleton, such as crabs and shrimp, because it captures both the living habitat and the protective outer covering that define crustaceans. The other choices describe mammals or birds, which are not crustaceans, and noting only a hard exoskeleton is too vague without mentioning the aquatic lifestyle and the broader arthropod relationship.