CIRCULATORY SYSTEM OF PIGEON

INTRODUCTION The circulatory system of pigeon, like all birds, is a marvel of efficiency and specialization, enabling them to meet the high metabolic demands of flight and other aspects of their active lifestyle. This essay explores the anatomy, function, adaptations, and comparative aspects of the circulatory system in pigeons. ANATOMY…

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CIRCULATORY SYSTEM OF REPTILES

INTRODUCTION The circulatory system of reptiles is a vital component of their physiology, enabling efficient transport of oxygen, nutrients, and waste products throughout their bodies. Unlike mammals and birds, reptiles exhibit a range of adaptations in their circulatory systems that reflect their evolutionary history and ecological niche. This essay explores…

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AERIAL ADAPTATIONS IN VERTEBRATES

The aerial adaptations are concerned with the flight. The flight is a form of locomotion in the air under which the body has to be firstly prevented from falling down and secondly moved forwards, the speedier the better. Thus, aerial adaptations must include modifications in the animals body for reducing the weight of the body and also for the formation of organs capable of executing the flight.

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GENERAL ORGANISTION OF GNATHOSTOMATA

The Gnathostomata includes all vertebrates with upper and lower jaws. It comprises a wide range of animals, from fish to the various tetrapod classes, which have in turn been derived from a fish or fish-like ancestor. An entirely satisfactory classification of fishes is not easy to construct, because of the incompleteness of several parts of the fossil record, and the consequent lack of connecting links.

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GENERAL ACCOUNT OF DIPNOI

The origin and evolution of Dipnoi remains problematic due to diverse opinions. They combine characteristics in which they resemble almost all the other groups of fishes as well as Amphibia. Fossil primitive Dipnoi (e.g. Diptems), shows geater similarity with fossil crossopterygians (e.g. Osteolepis), than do their living members.

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ORIGIN OF CHORDATA​ (PROTOCHORDATA AND EUCHORDATA)

We shall now consider the origin of the earlier chordate ancestors of vertebrates. That the chordates have originated from the invertebrates is not doubted by most zoologists now-a-days. Since the earlier chordate ancestors were all soft bodied forms, they left no fossil remains to give us clues as to origin of chordata. Therefore, the only basis for judging the origin of the group comes from the resemblances between the lower chordates (protochordates and the invertebrates).

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