General Characters:-

• The skin is smooth and slippery due to the presence of mucus. The skin is always maintained in a moist condition.
• The colour of dorsal side of body is generally olive green with dark irregular spots. On the ventral side the skin is uniformly pale yellow.
• The frog never drinks water but absorb it through the skin.
• Body of a frog is divisible into head and trunk A neck and tail are absent.
• Above the mouth, a pair of nostrils is present.
• Eyes are bulged and covered by a nictitating membrane that protects them while in water. On either side of eyes, a membranous tympanum (ear) receives sound signals.
• The forelimbs and hind limbs help in swimming, walking, leaping and burrowing.
• The hind limbs end in five digits and they are larger and muscular than the forelimbs that end in four digits. Feet have webbed digits that help in swimming.
• Frogs exhibit sexual dimorphism (male and female individuals of the same species are differentiated externally).
• Male frogs can be distinguished by the presence of sound-producing vocal sacs and also a copulatory pad on the first digit of the forelimbs which are absent in female frogs.