Shape and Size :
The body of frog is streamlined. It’s anterior end is narrow and the posterior end is broad and somewhat round. The length is about 12 to 18 cm and the width is 5 to 8 cm.
Skin Colour :
The frog is bounded by a soft, thin, smooth and slimy skin. It is loosely attached to the body. The skin color is green dorsally with lines and spots. Ventrally the skin is pale yellow in color. The skin of male frog is darker than female frog.
Body Division :
The body of the frog is divisible into head and trunk The neck is absent to avoid friction during swimming.
- Head : The head of the frog is triangular and narrow anterior. The snout is broad and blunt, and it bears a broad mouth a pair of external nares. The head bears a pair of large and projected eyes which are situated on both the dorso-lateral sides. Each eye is guarded by a pair of upper and lower eye lids which are movable. In addition, each eye has a third eyelid called nictitating membrance which is thin & transparent. It covers the eye inside the water.
The head also bears a pair of tympanum which are situated as dark and round patches below the eyes.
- Trunk : The trunk is broad, somewhat round and attached directly to the head. The trunk is attached with a pair of fore limbs and a pair of hind limbs. The fore limbs are relatively shorter and are tetradactylus (thumb is absent). The hind limbs are longer, Z-like, webbed and pentadactylus. The first finger of fore limb develops copulatory pad in male during the breeding season. It is used to hold the female during copulation. The fingers of both the fore limbs and hind limbs are without claws.
Frog exhibits sexual dimorphism and the characters are as follows-
- The male is darker than female.
- Male is comparatively bigger than female.
- The male has a pair of vocal sacs which become prominent during breeding season.
- The first finger of hand of male has a copulatory or amplexury pad which becomes prominent during breeding season. The pads are used to hold female during compilation.