Question

Compare the exoskeletons of two invertebrates: a grasshopper (Arthropod) and a clam (Mollusca). How do they differ in relation to support and movement?

Answer 1

Answer:

• Mollusca: Unsegmented exoskeleton, with no appendixes articulated to them. This skeleton has a calcareous origin.

• Arthropoda: Segmented exoskeleton, with different appendixes articulated to them, which develop different functions. This skeleton has a chitinous origin.

Explanation:

• Clams are bivalves. Their calcareous exoskeleton has two valves dorsally articulated to each other. They do not articulate with any appendix, although. These animals also have a foot, a small head, and a developed mantle cavity. The valves are convex, oval, and unsegmented. They are composed of three layers: periostracum, prismatic, and pearly. En the dorsal portion of each valve, there is a bulge called the umbo, which is the oldest part of the valve. The articulation has some teeth-shaped structures that are intercalated, maintaining the valves together and fixed.

• Grasshoppers have a chitinous exoskeleton divided into three principal segments or regions that allow their movement: head, thorax, and abdomen. The head is orientated in such a manner that their feeding apparatus is heading down. Also, the head segment has composed eyes and antennae. The thorax is the medial region of the body. It has three segments: the prothorax, mesothorax, and metathorax. Each of these segments articulates with a pair of legs. Finally, the abdomen is composed of many segments that might reach up to 7 or 11.