Amphibians are tetrapod vertebrates of the class Amphibia. The term derived from Greek Amphibios, Which means living a double life reflects this dual life strategy. They can live on both land and water. There are many different kinds of amphibians, but they all share the same characteristics, or special qualities, that make them different from other animals and easy to recognize. The species in this group include frogs, toads, salamanders, and newts. All can breathe and absorb water through their very thin skin.
Amphibians also have special skin glands that produce useful proteins. Some transport water, oxygen, and carbon dioxide either into or out of the animal. Others fight bacteria or fungal infections. And at least one in each species is used for defense. The class Amphibia is divided into 3 types:
- Anura, which includes the toads and frogs.
- Apoda, which comprises the caecilians.
- Urodela, which are mainly salamanders.
Characteristics of Amphibians
- Amphibians are strictly cold-blooded or ectothermic.
- They can Breathe Through Skin.
- Amphibians can live In Water and On Land.
- These are carnivores and feed on almost anything, and they can swallow.
Their metabolic rate is low and as a result, their food and energy requirements are limited. In the adult state, they have tear ducts and movable eyelids, and most species have ears that can detect airborne or ground vibrations. They have muscular tongues, which in many species can be protruded. The skin contains many mucous glands and in some species, poison glands. The hearts of amphibians have three chambers, two atria, and one ventricle. They have a urinary bladder and nitrogenous waste products are excreted primarily as urea. Most amphibians lay their eggs in water and have aquatic larvae that undergo metamorphosis to become terrestrial adults. Amphibians breathe through a pump action in which air is first drawn into the buccopharyngeal region through the nostrils. These are then closed and the air is forced into the lungs by contraction of the throat. They supplement this with gas exchange through the skin.
- The largest amphibian is the giant salamander at 4 feet 8 inches long.
- The smallest amphibian in the world Paedophryne amauensis, at only 0.30 inches.