In this article we will discuss about:- 1. Origin of Cyclostomes 2. General Characters of Cyclostomes 3. Classification 4. Representative Types 5. Affinities. Origin of Cyclostomes: The Cyclostomata (Gr., cyklos = circular + stoma = mouth) are the living agnathans, they are primitive in many respects, but specialised in others. They are a modified and degenerate offshoot of the primitive [...]
In this article we will discuss about the external features of lamprey with the help of suitable diagrams. Also learn about its habit and habitat. Shape and Size: The body of adult Petromyzon is elongated, cylindrical and eel-like. Petromyzon marinus (sea-lamprey) attains a length of a metre, Lampetra fluviatilis (Lampern or common freshwater lamprey) reaches a length of about 90 [...]
The digestive system of pigeon is well developed and includes an alimentary canal and the digestive glands. Alimentary Canal: The alimentary canal of pigeon (Fig. 26.28) is long, tubular and coiled. It comprises mouth, buccal cavity, pharynx, oesophagus, stomach, small intestine and large intestine which opens to the exterior by cloacal aperture. All the segments of alimentary canal fall into [...]