More on Frogs

SCIENTIFIC CLASSIFICATION: True frogs make up the family Ranidae.

TIME PERIOD: The first frogs came on earth 180 million years ago.

HABITAT: They live in every continent but for Antarctica. Most of them live part of their life in water, and the rest on land.

DESCRIPTION:

The frog's body

Frogs differ in sizes and colour. They all have some common features though. The have large hind legs, short front ones, flat heads and no neck. The adult frogs have no tails.

Most have a sticky tongue, attached in the front and free at the back. This helps the tongue shoot out farther. They all have internal organs like heart, liver, lung and kidney's. The internal organs are different from the higher animals. They have a three chambered heart. They breathe by lungs and skins.

Frogs have powerful hind legs ( except those that burrow into the ground ) and can leap 20 times their body length. They also use it for swimming. They have webbed feet and suckers on their fingers. They help it to cling to the surface.

They have moist skins, with some poison glands in some cases.They have no hair. If an enemy grabs the frog, the poison is secreted through the skin, making the enemy release the frog. Frogs shed their skin a few times a year.

Frogs have good eyesight. They can see in most directions. They have a membrane in their eyes known as nictitating membrane that help protect the eye. The membrane is transparent.

Behind the eyes, there is a patch or disk that is the tympanum and helps the frog in hearing. Most male frogs have a voice that is loud, unlike the female voice. It is often used to call the female in the mating season. The voice is produced by the vocal cords that vibrates. Most males have a sac, that swells up en the voice is being made, to produce a larger sound.

ITS PART IN EVOLUTION TABLE: Frogs come under the class Amphibia under Vertebratea under the Animal Kingdom.