Chapter 26, Problem 13STP

Summary Introduction

To analyze:

The characteristics of mollusks.

Introduction :

Mollusks are considered as the second largest phylum that includes the soft body invertebrates. They are enclosed inside a calcium carbonate shell that protects their soft body. They are found in almost all habitats except air, they are mostly marine, gastropods, and bivalves. They undergo sexual reproduction by the fusion of gametes. During external fertilization they lay eggs and the egg fertilized by the male outside the female body.

Explanation of Solution

The mollusks have many different characteristics that differentiate them from other organisms. Some characteristics may also vary between species to species in the phylum mollusks. The characteristics that all mollusks have in common are: they have bilaterally symmetrical with unsegmented soft body, they all have internal and external shell, all have toothed tough made of chitin that is named as Radula. They have a fold in the body wall called mantle that lines the shell, and all have muscular foot.

Conclusion

All the organisms of mollusks have same body symmetry; shell is either external or internal, structure of tongue, presence of mantle, and muscular foot.