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 coelom of birds (pigeon) is well developed and divided into two cavities, anterior thoracic and posterior abdominal cavities, by a membranous oblique septum or diaphragm. The thoracic cavity has two dorso-lateral pleural cavities, each enclosing a lung. The two pleural cavities are separated from each other by the antero-ventral pericardial cavity enclosing the heart lying in the middle between [...]