EVERYDAY SCIENCE

Detailed explanation-1: -Which of the following is a correct description of the polyp body form? It is sessile and the tentacles and mouth point downward.

Detailed explanation-2: -The polyp has a tubular body and is usually sessile. The medusa(plural, medusae) has a bell-shaped body and is typically motile. Some cnidarian species alternate between polyp and medusa forms. Other species exist in just one form or the other.

Detailed explanation-3: -The polyp form has a body shaped like a hollow cylinder or a bag that opens and closes at the top (Fig. 3.25 A). Tentacles form a ring around a small mouth at the top of the bag. The mouth leads to a central body cavity, the gastrovascular cavity (Fig.

Detailed explanation-4: -The polyp may be solitary, as in the sea anemone, or colonial, as in coral, and is sessile (attached to a surface). The upper, or free, end of the body, which is hollow and cylindrical, typically has a mouth surrounded by extensible tentacles that bear complex stinging structures called nematocysts.

Detailed explanation-5: -Almost all corals are colonial organisms. This means that they are composed of hundreds to hundreds of thousands of individual animals, called polyps. Each polyp has a stomach that opens at only one end. This opening, called the mouth, is surrounded by a circle of tentacles.