Which group has an exoskeleton and segmented body?

Which group has an exoskeleton and segmented body?

• A. Echinoderms
• B. Mollusks
• C. Annelids
• D. Arthropods

Answer: (D)

Arthropods have a hard outer covering called an exoskeleton and a body that is clearly segmented, with jointed appendages extending from those segments. The exoskeleton, made mainly of chitin, provides protection and helps prevent water loss, which is especially useful for insects and other terrestrial arthropods. The segmentation is evident in distinct body regions (like head, thorax, and abdomen in many groups) and allows specialized, jointed limbs for a wide range of movements and functions. Echinoderms, such as starfish and sea urchins, have an internal or beneath-skin skeleton and exhibit radial symmetry rather than a clearly segmented body plan. Mollusks often have shells as armor but do not show a segmented body with jointed limbs in the way arthropods do. Annelids, like earthworms, have segmented bodies, but they lack an external exoskeleton; their support comes from internal fluids rather than a hard outer shell. So the combination of an exoskeleton and segmented body is a defining feature of arthropods, which include insects, spiders, crustaceans, and many other familiar animals.

Arthropods have a hard outer covering called an exoskeleton and a body that is clearly segmented, with jointed appendages extending from those segments. The exoskeleton, made mainly of chitin, provides protection and helps prevent water loss, which is especially useful for insects and other terrestrial arthropods. The segmentation is evident in distinct body regions (like head, thorax, and abdomen in many groups) and allows specialized, jointed limbs for a wide range of movements and functions.

Echinoderms, such as starfish and sea urchins, have an internal or beneath-skin skeleton and exhibit radial symmetry rather than a clearly segmented body plan. Mollusks often have shells as armor but do not show a segmented body with jointed limbs in the way arthropods do. Annelids, like earthworms, have segmented bodies, but they lack an external exoskeleton; their support comes from internal fluids rather than a hard outer shell.

So the combination of an exoskeleton and segmented body is a defining feature of arthropods, which include insects, spiders, crustaceans, and many other familiar animals.