The swift straightening of the fully flexed hindlimbs give a jerk or thrust and acceleration required for progression.įorelimb has four digits and hindlimbs have five digits. Hindlimbs are long and consist of (i) thigh (ii) shank or crus (iii) and a foot or pes bearing 5 digits or toes.ĭuring rest, hindlimbs are flexed in the form of Z with knee pointing forward and outward and feet resting upon the ground toes of hind limbs are joined together by a thin web of skin fold which is an adaptation for both leaping and swimming. (iii) A hand or manus bearing 4 digits or fingers. It receives sound waves from the environment. The main distal part of it is a thin transparent nictating membrane which completely covers the eyes to protect them from water or mud without affecting normal vision.Ī vestige of a functional third eye is present as a small, circular and light coloured brown spot in between two eyes.īehind each eye is present a deep pigmented circular patch of tough membrane-like skin, called eardrum or tympanic membrane. This compensates the absence of neck.Įyes are provided with a pair of eyelids. The frog can rotate its eyes in different directions. Eyes are located in large depressions of the soft skin of the roof of buccopharyngeal cavity. These valves keep the external nares closed while in water or during hibernation/aestivation.Ī pair of large spherical & protruding eyes are located almost laterally upon top of the head. It leads into nasal chambers which open by internal nares/ choanae into anterior part of the buccal cavity.Įxternal nares are guarded by a membranous valve. Cheeks and lips are absent.Ī pair of small circular external nares/nostrils are located at the tip on dorsal side. These features help it in burrowing in mud during hibernation (winter sleep) or aestivation (summer sleep). The head is flat and triangular with blunt snout. ![]() Tail is present only with its larval form (tadpole larva). The frog body is divisible into two parts : head and trunk. Its body colour offers it protection from the enemies (protective colouration camouflage). The body is spotted olive green on the dorsal side & is pale yellow on the ventral side. The size of body is also helpful in its movement. It is somewhat spindle-shaped and streamlined so as to get least resistance during swimming in water or hopping in air. The body of a frog is dorsoventrally flattened. Males produce louder sound as compared to the females due to the presence of a pair of distensible balloon-like vocal sacs, which act as resonators. ![]() The characteristic noise or sound produced by frogs is called croaking. Nupital pads help male in holding female, a sexual embrace called amphlexus (false copulation). Male and female frogs are distinguishable externally only during breeding season when the males develop roughened nuptial pads on the bases of the thumb. The dorsal surface of frog is spotted olive green and ventral pale yellow this protective colouration help to camouflage, i.e., escape the detection by enemies. It never drinks water, absorbs water through skin. They become metabolically inactive and stop feeding, respire only with skin, i.e., cutaneous respiration. Found all over world except Australia, New Zealand.īeing cold-blooded or poikilothermous (the body temperature changes with environment) frogs undergo aestivation or ‘summer sleep’ in summer and hibernation ‘winter sleep’ in winter. ![]() Most common frog found in India is the Indian bullfrog Rana tigrina found in or near freshwater lakes, streams and ponds.
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