3Amphibian Classification Notes Amphibians occur on all continents except Antarctica.There are about 4000 living species of amphibian.These species belong to 3 orders:1. Caudata2. Gymnophiona3. Anura
4ORDER CAUDATA Members of this order are the salamanders. They possess a tail throughout their life and may or may not have legs.
5ORDER CAUDATAThere are about 350 species of salamander and almost half of these live in North America.Most salamanders that live on land (terrestrial) live on the forest floor and have aquatic larvae.
6ORDER CAUDATAMembers of the family Salamandridae are commonly called newts.They spend most of their time in water and will often keep their fins.
7ORDER CAUDATASalamanders range in length from a few centimeters to 1.5 meters (Japanese giant salamander)The largest North American salamander is the hellbender, which gets about 65 centimeters.
9ORDER CAUDATA Most salamanders have internal fertilization. Males produce a jelly-like substance that contains their sperm and the females pick up and store the sperm in a special pouch called the spermatheca.Eggs are deposited in clumps or strings.Larvae are similar to adults but smaller.Many salamanders will undergo incomplete metamorphosis and are paedomorphic—become sexually active while still having larval characteristics.
11ORDER GYMNOPHIONA Members of this order are the caecilians. There are about 160 species, found mostly in tropical regions.
12ORDER GYMNOPHIONACaecilians are wormlike burrowers that feed on worms and other invertebrates in the soil.Caecilians appear segmented because of folds of skin that cover separations between muscles.
13ORDER GYMNOPHIONAThey have a retracting tentacle between their eyes and nostrils that may transport chemicals from the environment to sensory cells in the roof of the mouth.Skin covers their eyes so they are nearly blind.
14ORDER GYMNOPHIONA Fertilization is internal. Larval stages often occur inside the female.The young emerge from the female as miniature adults.Some caecilians will lay eggs that develop into aquatic larvae.
15ORDER ANURA This order contains frogs and toads. There are about 3500 species.Anurans live in moist environments, except in high latitudes.Adults do not have tails.Hindlimbs are long and muscular and end in webbed feet.
16ORDER ANURAFertilization is almost always external, and eggs and larvae are usually aquatic.The larval stage is called a tadpole and has a well-developed tail.
17ORDER ANURAThey have no limbs until almost the end of the larval stage.Larvae are herbivores and have a beaklike structure for feeding.These larvae undergo a drastic and rapid metamorphosis to the adult body form.