In this article we will discuss about the Structure of a Typical Fish. Fishes are cold blooded animals, typically with backbone, gills and fins. The body of a typical fish comprises the head, trunk and tail. The head bears two eyes, with well developed nictitating membrane, two internal ears, two nostrils which are closed internally (except in lung fishes) and [...]
The below mentioned article provides biology notes on Class Osteichthyes. 1. The endoskeleton is cartilaginous in the embryonic stage, but in the adult forms more or less it is replaced by bones. Thus they have bony endoskeleton. They are ectothermic (cold blooded). There are about 25,000 species of bony fishes. 2. Caudal fin usually homocercal symmetrical (Gr. homos- alike). 3. [...]
The below mentioned article provides short notes on Class Chondrichtyes. 1. The fishes of this class bear cartilaginous endoskeleton. They are cold blooded (poikilothermous or ectothermic). There are about 600 species of cartilaginous fishes. 2. The skin is tough, containing minute placoid scales, which are dermal in origin. 3. Except in the Chimaeras, the gills are not covered by an [...]