![]() True frogs (like the wood frog shown in the image above) tend to have two bulging eyes, strong, long, webbed hind feet that are adapted for leaping and swimming, smooth or slimy skin. There are over 4,000 species of frogs and toads, ranging in size from 1 cm to over 30 cm! These amphibians lack tails and are therefore referred to as anurans. Consequently, they tend to be colorful, active during the day and quite bold (contrasted to most other species of salamanders, which are nocturnal). Another difference is that newts tend to be poisonous, and some of them are quite deadly if ingested. ![]() In North America, newts tend be more aquatic with laterally compressed tails that aid in swimming. There is little actual distinction between newts and salamanders. Lungs are the rule in adult forms, but some salamanders lack lungs or gills, using only their skin and mouth for gas exchange! Newts All salamanders and newts hatch with gills, but these are usually lost in all but aquatic forms or those that fail to metamorphose. Unique among vertebrates is the ability to regenerate lost limbs, as well as other body parts. Some salamanders are aquatic throughout life, some take to the water intermittently and some are entirely terrestrial as adults. Their moist skin restricts them to moist habitats in or near water, often in wetlands. Most species (like the Eastern red-backed salamander shown) have slender bodies, short noses, long tails and four toes on their front legs and five on their rear legs. Salamanders are tailed amphibians with short, stubby legs. Their food consists mostly of earthworms and other small invertebrates. The caecilians include about 165 limbless amphibians that inhabit tropical forests of Central and South America, Africa and Southeast Asia. Living amphibians include the: leg-less amphibians (caecilians), tailed-amphibians (salamanders and newts) and tail-less amphibians, or anurans, (frogs and toads). These colors are due to pigment-containing cells call chromatophores that come in several varieties. In keeping with their toxic nature, many amphibians are brightly marked with aposematic (warning) colors that advertise their toxicity. The skin of all amphibians also contains poison (serous) glands that produce toxins that range from mildly noxious to deadly poison (some are among the most potent toxins produced by any vertebrates). Since it is too thin to provide much protection against dehydration or predators, they must employ other means of defense.įor example, amphibian skin contains many mucous glands that keep them moist and make them slippery, which helps them escape from predators. ![]() The skin of amphibians is moist and thin with no scales. General characteristics of amphibians include a bony skeleton and usually four limbs. Amphibians make their first appearance in the fossil record almost 400 million years ago, and the surviving species represent a small fraction of the total number of amphibians that once existed on Earth. The Class Amphibia ("double life") contains over 4,000 species of animals that are somewhat transitional between fishes and reptiles.
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