Master Notes on Cnidarians:- 1. Protohydra 2. Halistemma 3. Physalia 4. Porpita 5. Velella 6. Diphyes. Cnidarian # 1. Protohydra: Protohydra (Fig. 12.29A) is a peculiar hydra of 3 mm in length. It lacks the usual tentacles. It is available along the shores of Great Britain and northern part of Europe. Protohydra feeds on nematodes and small crustaceans and propagates [...]
In this article we will discuss about the histological organisation of Cnidarians. 1. Ectoderm: In most cases it is distinctly cellular. Presence of ciliated ectoderm in larval cnidarians is usually seen. The cellular ectoderm is mainly composed of the supporting cells, called the Epitheliomuscular cells. They are usually cuboidal or columnar in shape. They may be thin and flattened (exumbrellar [...]
In this article we will discuss about Polymorphism in Cnidarians:- 1. Definition of Polymorphism 2. Causes of Polymorphism 3. Basic Units 4. Origin 5. Significance. Definition of Polymorphism: Polymorphism may be defined as the "phenomenon of existence of different physiological and morphological forms represented by an extensive range of variation within a single species". It may be defined in another [...]