`star` Introduction
`star` External Surface
`star` External Organs


● Frogs can live both on `color{violet}("land")` and in `color{violet}("freshwater")` and belong to class `color{violet}("Amphibia of phylum Chordata.")`

● The most common species of frog found in India is `color{brown}("Rana tigrina.")`

● They do not have constant `color{violet}("body temperature")` i.e., their body temperature varies with the temperature of the environment.

● Such `color{violet}("animals")` are called `color{violet}("cold blooded or poikilotherms.")`

● There are also changes in the `color{violet}("colour of the frogs")` while they are in `color{violet}("grasses")` and on `color{violet}("dry land.")`

● They have the ability to change the colour to hide them from their enemies ( `color{brown}("camouflage")`).

● This `color{violet}("protective coloration")` is called `color{brown}("mimicry.")`

● The `color{violet}("frogs")` are not seen during peak summer and winter.

● During this period they take shelter in deep burrows to protect them from `color{violet}("extreme heat and cold.")`

● This is called as summer sleep ( `color{brown}("aestivation")`) and winter sleep ( `color{brown}("hibernation")`).


● The skin of frog is `color{violet}("smooth and slippery")` due to the presence of `color{brown}("mucus.")`

● The skin is always maintained in a `color{violet}("moist condition.")`

● `color{brown}("The colour of dorsal side of body is generally olive")` green with dark irregular spots.

● On the ventral side the skin is `color{brown}("uniformly pale yellow.")`

● The frog `color{violet}("never drinks water")` but absorb it through the skin.

● Body of a frog is divisible into `color{violet}("head and trunk.")`

● A `color{violet}("neck and tail")` are absent.


● Above the mouth, a `color{brown}("pair of nostrils")` is present.

● Eyes are bulged and covered by a `color{violet}("nictitating membrane")` that protects them while in water.

● On either side of eyes a `color{brown}("membranous tympanum")` (ear) receives sound signals.

● The `color{brown}("forelimbs and hind limbs help")` in swimming, walking, leaping and burrowing.

● The `color{violet}("hind limbs end")` in five digits and they are larger and `color{violet}("muscular")` than fore `color{violet}("limbs")` that end in four digits.

● Feet have `color{brown}("webbed digits")` that help in swimming.

● Frogs exhibit `color{violet}("sexual dimorphism.")`

● Male frogs can be distinguished by the presence of sound producing `color{violet}("vocal sacs")` and also a `color{violet}("copulatory pad")` on the first digit of the fore `color{violet}("limbs")` which are absent in `color{violet}("female frogs.")`