About Frogs

History

• The first true frog existed more than 200 million years ago. There is only one specimen of the vieraella herbsti, which is little more than 3 centimeters long. Unlike its predecessor, Gerobatrachus hottoni, the vieraella herbsti shows traits that are distinctly froglike. The Gerobatrachus hottoni, however, has been reconstructed as a cross between a frog and a salamander, showing a bone structure that is similar to a salamander with the ear structures of a frog. This is generally considered to be a missing link, demonstrating that frog and salamanders have a common ancestor. The Gerobatrachus hottoni was found in the area that is now Texas and is estimated to have lived nearly 300 million years ago.

  Frogs as they exist now have been found in the fossil record from as long ago as 125 million years, making them a modern-day dinosaur.

Identification

• Frogs are set apart from other members of the amphibian family by several unusual traits; while there are approximately 5,200 different types of frogs, there are still certain traits that are common throughout.

  The frogs' skin allows oxygen to pass through it, effectively allowing them to breathe through their skin. Consequently a frog's skin must always be moist. This makes them particularly sensitive to pollution, which in some areas has been a cause of species becoming endangered or extinct.

  Frogs begin their lives as tadpoles but all lose their tails as adults. They have hind legs that are better suited for jumping rather than walking. The legs make up the majority of the body; the main trunk of the frog's body is squat and round in comparison.

  Frogs have three eyelids, one of which is used to protect the eyes when the frog is underwater while the other two are used above water. Their ears are on the sides of their heads, and the majority of frogs have a row of teeth on their upper jaw. The teeth are used to hold their prey while they kill it; since their teeth are only on the upper jaw, they cannot chew and swallow their prey whole instead.

  Frogs are the best jumpers of all animals with a backbone, with most able to jump many times the length of their body. The Australian rocket frog can jump 50 times the length of its own body, equivalent to a 6-foot-tall human jumping 300 feet.

  A group of frogs is called an "army."

Geography

• Frogs are found in every area of the world except near the North and South poles, the Sahara Desert and parts of Saudi Arabia.

Size

• The largest known frog is the Goliath frog, which can grow up to 13 inches long and weigh up to eight pounds. The frog has a small and rapidly diminishing habitat on the western coast of Africa near Gabon. Their dwindling habitat and popularity as pets (in spite of the fact that they're difficult to keep in captivity) has put such a strain on the wild population that they are now regulated by the government.

  The smallest known frog is the Brazilian gold frog. Adults grow to be approximately 9 millimeters in length, less than half the size of an American dime.

Misconceptions

• Warts cannot be transmitted from frogs to humans just by touching them.

Theories/Speculation

• New frogs are still being discovered. Since some are extremely tiny and exist only in small, specific locations -- like the recently discovered golden frog of Supata -- they're very difficult to catch, study and classify. The golden frog of Supata lives only in a 20-hectare area in Colombia, a country that is already known for an impressive diversity in amphibian life. Also recently discovered is the tiny, 10-millimeter Nyctibatrachus minimus, also known as the nightfrog. This frog, found in the rainforests of the Western Ghats in India, shows how little we know about the animal life of the rainforests. Not long before the new nightfrog and golden frog were discovered, six new species were found in Laos.

  There is no way to tell how many different species of frogs exist, especially in densely populated and forested areas. The current estimation of 5,200 different types of species only represents those that have been discovered. With the rapid deforestation that is occurring around the world, there also is no way to tell how many species have become extinct before we have even been able to identify them.