Post on 27-Mar-2015
transcript
Amphibian Classification
Amphibian 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
ORDER CAUDATA
• Members of this order are the salamanders. • They possess a tail throughout their life and may
or may not have legs.
ORDER CAUDATA
• There 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.
ORDER CAUDATA
• Members of the family Salamandridae are commonly called newts.
• They spend most of their time in water and will often keep their fins.
ORDER CAUDATA
• Salamanders 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.
ORDER 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.
ORDER GYMNOPHIONA
• Members of this order are the caecilians. • There are about 160 species, found mostly in
tropical regions.
ORDER GYMNOPHIONA
• Caecilians 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.
ORDER GYMNOPHIONA
• They 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.
ORDER 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.
ORDER 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.
ORDER ANURA
• Fertilization is almost always external, and eggs and larvae are usually aquatic.
• The larval stage is called a tadpole and has a well-developed tail.
ORDER ANURA
• They 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.
ORDER ANURA
• The distinction between “frog” and “toad” is not very scientific.
• “Toad” usually refers to anurans with dry and warty skin and are more terrestrial than other members of this order.