What is the name of the thickened region of the exoskeleton that covers the cephalothorax?
A shell
B maxillae
C carapace
D telson
E maxillopod
The correct answer and explanation is:
The correct answer is C. carapace.
The carapace is a thickened region of the exoskeleton that covers and protects the cephalothorax, which is the combined head and thorax region of some arthropods, including crustaceans like crabs, lobsters, and shrimps. The carapace is made of chitin, a strong and flexible substance, which gives structural support and protection to the internal organs. It serves as a protective shield from predators, environmental stressors, and physical damage.
In crustaceans, the carapace may extend over the head and sometimes partially over the abdomen. It can also have various specialized features depending on the species. For instance, in some species, the carapace has spines or ridges, which provide additional defense or help with streamlining during movement through water.
The carapace plays an important role in the overall biology of these organisms. As arthropods grow, their exoskeleton (including the carapace) does not grow with them, which necessitates the process of molting or ecdysis. During this process, the exoskeleton is shed, and a new, larger exoskeleton forms. This allows the organism to grow and develop without being constrained by the old exoskeleton. The timing and frequency of molting vary between species and are influenced by environmental conditions, nutritional factors, and the life stage of the organism.
In contrast, the maxillae (B) are appendages involved in feeding, the telson (D) is the terminal part of the abdomen in some arthropods, and maxillopods (E) refer to a group of crustaceans. A shell (A) is a general term that could refer to various hard external structures, but it is not specific to the carapace.