Chapter 26, Problem 21A

Summary Introduction

To write:

About the molting of crustaceans

Introduction:

Crabs, lobsters, shrimps, barnacles, pill bugs, and water fleas are crustaceans that live in freshwater, marine, and terrestrial habitats. It is estimated that approximately 35,000 named species of class Crustacea are present. Many of them are aquatic and have two pairs of antennas, two compound eyes which are sometimes on the ends of slender mobile stalks, and mandibles to chew. Crustacean mandibles close and open from side to side, instead of going up and down like human jaws do. Crustaceans have branched appendages and a free-swimming larval stage, called the larva nauplius. A larva is an immature form of a species, markedly different from the adult in shape and appearance.

Explanation of Solution

All crustaceans have a hard exoskeleton that protects the animal against predators and prevents loss of water. Exoskeletons, though, do not grow as the animal grows inside them, so crustaceans are forced to molt as they grow bigger. The process of molting takes from a few minutes to several hours. A soft exoskeleton underneath the old one forms during molting, and the old exoskeleton is removed. This is a vulnerable time for the crustacean, as the new exoskeleton is soft, until it become hardens. Crustaceans typically expand their bodies immediately after molting, increasing by 40 percent to 80 percent. If crustacean do not molt then it will be difficult for the animal to grow inside the exoskeleton so they molt to grow. They grow their exoskeleton to get a bigger one.

Conclusion

So it can be concluded that molting is necessary for the growth and development of crustaceans.