Frogs :: essays research papers fc

Frogs are needed for everyday life. They are part of pond life. Each animal is important because even in the pond, there is a food chain. Frogs are amphibians, animals that spend half of their lives under water, and remainder on land. The first frog appeared in the early Jurassic period about 200 million years ago.   Ã‚  Ã‚  Ã‚  Ã‚  Frogs live on every continent except Antarctica, but tropical regions have the largest amount. Like all amphibians, frogs spend half their lives near water because they must return to the water to lay their eggs. Frogs live underwater mostly when the are growing up to be an adult frog and when they are laying their eggs. When they hatch under water they are tadpoles and the breath with gills and swim using a tail. As they mature they loose their tail and they develop to be able to breathe air. During an extensive period of heat, a drought, frogs can enter a period of damancy similar to hibernation called starvation. Most of the frogs live in tropical and semitropical regions, most species of frogs breed in the spring or in early summer. Although the different species my vary in size and color, mostly all frogs have basic body structure. They have large hind legs, short front legs and flat head and body with no neck.   Ã‚  Ã‚  Ã‚  Ã‚  Most frogs have teeth only on their upper jaw. Toads swallow their prey in one piece. To aid in the swallowing process, the frog’s eyes sink through the openings in the skull and force the food down its throat. Frogs eat insects, catching them with their long sticky tongue. They also eat small fish and worms. They also absorb concentrate to make them stronger, and toxins (poisonous substances) in their fatty tissues.   Ã‚  Ã‚  Ã‚  Ã‚  Since the 1980’s scientists have noted the decline of many frog species. People do not know for certain what has caused these declines. A possible factor is pollution, disease, habitat destruction, and acid rain. Another factor may be the thinning of the earth’s protective ozone layer, which allows more harmful ultraviolet radiation from the sun to reach the earth. Because frogs have thin, moist skin and an aquatic tadpole stage, they are easily affected by pollution and changes in the environment.