Which groups are arthropods?

Which groups are arthropods?

• A. Insects and Arachnids
• B. Mammals and Birds
• C. Reptiles and Fish
• D. Amphibians and Mollusks

Answer: (A)

Arthropods share key features: an exoskeleton, a body that is segmented, and jointed appendages. Insects and arachnids fit this group best. Insects have a three-part body (head, thorax, abdomen) with six legs, while arachnids have two main body sections and eight legs. The other groups aren’t arthropods because mammals and birds are vertebrates with backbones, reptiles and fish are also vertebrates, and while mollusks are invertebrates, they lack the segmented bodies and jointed limbs that define arthropods.

Arthropods share key features: an exoskeleton, a body that is segmented, and jointed appendages. Insects and arachnids fit this group best. Insects have a three-part body (head, thorax, abdomen) with six legs, while arachnids have two main body sections and eight legs. The other groups aren’t arthropods because mammals and birds are vertebrates with backbones, reptiles and fish are also vertebrates, and while mollusks are invertebrates, they lack the segmented bodies and jointed limbs that define arthropods.