In this article we will discuss about the habit, habitat and life history of Obelia. Habit and Habitat of Obelia: Obelia is a typical representative of colonial hydrozoa (Fig. 12.14). It is exclusively marine. It exists in two principal forms, the polyp and the medusa. The polyp or hydroid form represents the asexual phase of its life-history and the medusoid [...]
The following points highlight the two main types of polymorphic variabilities in Siphonophora. 1. Modifications of the Polyp: A. Gastrozooids or Trophozooids or Nutritive Zooids: Characters: 1. It is like a typical polyp (Fig. 12.34A,B). 2. Each gastrozooid is a cylindrical and funnel-shaped body with a large mouth. 3. Presence of a well-formed coelenteron. 4. A single long contractile and [...]
In this article we will discuss about Hydra:- 1. Habit and Habitat of Hydra 2. Structure of Hydra 3. Structure and Function of the Different Cellular Units 4. Locomotion 5. Nutrition 6. Respiration and Excretion 7. Reproduction 8. Life History. Contents: Habit and Habitat of Hydra Structure of Hydra Structure and Function of the Different Cellular Units of Hydra Locomotion [...]