External Features (Morphology) of Frog (Rana tigrina)

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External Features of FrogBiology | Zoology Notes
External Features (Morphology) of Frog (Rana tigrina)
For: Science Class 11

Frog lives in fresh water, moist and damp place. They are poikilothermic (cold blooded). Frog becomes active in rainy season and they breed in rainy season. In winter and summer season, they live under soil and are inactive. The winter period is called hibernation and summer period is called aestivation. During hibernation and aestivation, they utilize food stored in their body.

External features of frog
The body is bilaterally symmetrical and dorsoventrally flattened. Skin is moist, smooth, and slippery. On the dorsal side, there is mid dorsal line running from head to tail. Ventral side is pale –yellow in colour and dorsal side is dark green with dark patch. Body is divided into head and trunk. In each eye, there are two eyelids. Upper eyelid ids immovable and eyelid is movable. There is third eyelid arising from lower eyelid, which is thin and transparent called nictitating membrane. It is freely movable and protects eye from dirty water. male frog have vocal sac on either side of throat which produces croaking sound to attract female in breeding season.

Skin:- skin is moist, smooth. The outer most layer is epidermis. Below epidermis, two glands are present. Poison gland and mucous gland. Mucous gland secretes a kind of watery fluid called mucin, which keeps skin moist.

Function – skin is protecting covering of the body. Mucous gland are present on the which secrete mucin and keeps the skin moist. Poison glands are also present in the skin, which protects from enemy. Frog does not drink water but water but water is absorbed through skin.

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