Question

Write the main features of class amphibia.

Answer 1

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• They are amphibious in nature i.e inhabit both water and land. 
• Solitory, free living, free swimming and poikilothermic. 
• Body is divisible into head, trunk and tail. The tail may be absent. 
• Absence of exoskeleton 
• Skin is soft slimy. 
• Respiration by gills, skin and lungs. 
• The skull is dicondyllic. 
• RBC are nucleated and biconvex. 
• The heart is 3 – Chambered (2 auricles and 1 ventricle) 
• They exhibit hibernation and aestivation 
• Presence of middle and internal ear. The middle ear has Columella auris structure. 
• They are ureotelic. Kidneys are mesonephric. 
• Presence of sinus venosus in the heart. 
• Presence of 3 pairs of aortic arches viz – Carotid arches – 1 pair, Systemic arches – 1 pair and Pulmonary arches – 1 pair. 
• External fertilization and indirect development. 
• Oviparous and eggs are mesolecithal 
• The larva is tadpole. Some have axolotle larva.