The frog is an amphibian in the order Anura (meaning "tail-less") There are around 5,250 species of frogs and about 88% of amphibians are frogs! From a taxonomic perspective, all members of the order Anura are frogs, but only members of the family Bufonidae are considered "true toads". The common use of the name "frog" usually refers to species that are aquatic or semi-aquatic with smooth and/or moist skins. The name "toad" generally refers to species that tend to be terrestrial with dry, warty skin.

Most frogs are characterized by long hind legs, a short body, webbed fingers and toes, protruding eyes and the absence of a tail. Most frogs have a semi-aquatic lifestyle, but move easily on land by jumping or climbing. They typically lay their eggs in puddles, ponds or lakes, and their larvae, called tadpoles, have gills and develop in water. Adult frogs follow a carnivorous diet, mostly of arthropods, annelids and gastropods. Frogs are most noticeable by their call, which can be widely heard during the night or day, mainly in their mating season.

Feet and Legs

The structure of the feet and legs varies greatly among frog species, depending in part on whether they live primarily on the ground, in water, in trees, or in burrows. Frogs must be able to move quickly through their environment to catch prey and escape predators, and numerous adaptations help them do so.Many frogs, especially those that live in water, have webbed toes. The degree to which the toes are webbed is directly proportional to the amount of time the species lives in the water.

Jumping

Frogs are generally recognized as exceptional jumpers, and the best jumper of all vertebrates. The Australian rocket frog, Litoria nasuta, can leap over 50 times their body length (5.5 cm), resulting in jumps of over 2 meters.

Skin

Many frogs are able to absorb water and oxygen directly through the skin.Some tree frogs reduce water loss with a waterproof layer of skin. Others have adapted behaviours to conserve water, including engaging in nocturnal activity and resting in a water-conserving position. This position involves the frog lying with its toes and fingers tucked under its body and chin.

Camouflage is a common defensive mechanism in frogs. Most camouflaged frogs are nocturnal, which adds to their ability to hide. Nocturnal frogs usually find the ideal camouflaged position during the day to sleep. Some frogs have the ability to change colour, but this is usually restricted to shades of one or two colours. For example, White's tree frog varies in shades of green and brown. Features such as warts and skin folds are usually found on ground-dwelling frogs, where a smooth skin would not disguise them effectively.

Life Cycle

The life cycle of a frog starts with an egg. A female generally lays frogspawn, or egg masses containing thousands of eggs, in water. Eggs hatch and continue life as tadpoles (occasionally known as polliwogs), which typically have oval bodies and long, vertically-flattened tails. At the end of the tadpole stage, frogs undergo metamorphosis, in which they transition into adult form. Metamorphosis involves a dramatic transformation of morphology and physiology, as tadpoles develop hind legs, then front legs, lose their gills and develop lungs. Their intestines shorten as they shift from an herbivorous to a carnivorous diet.