Question

1. Describe the 2 major body regions of a typical mollisk?
2. Annelids exhibit body segmentation. why is this a major evolutionary innovation?
3. Why are insects so successful??

Answer 1

1) Two major body regions of a typical mollusk:

Mollusks are invertebrate animal. They share in common a three-part body plan, which includes a head, a foot and a visceral mass.

The Foot : They have foot. The foot is responsible for movement. Some mollusks use their foot to attaching to rocks and grasping prey. The foot is divided into separate arms, which can develop to 45 feet long in some species. Clams and other bivalves feet help them dig into the mud for their safety.

The Visceral Mass : The visceral mass includes all of the mollusk's organs. These organs include a three-chambered heart in most mollusks and three separate hearts in cephalopods. All mollusks have highly developed tubes, which act their kidney functions. They have one-way digestive tracts in which food transfers from the stomach to the intestine and out the anus. They do not have fully developed lungs. Aquatic mollusks breathe with the help of gills and land mollusks have membranes that operate as primitive lungs. Extending from the visceral mass is a protective tissue fold called as the mantle.