What type of covering do amphibians have

The males of most species call to attract mates in a lively chorus, while voiceless salamanders and toads search for their mates by smell. Generally, mating and egg-laying take place in the water, where eggs and young are left to fend for themselves. However, some salamanders lay their eggs in rotten logs or in moss on the edge of ponds and several salamander species stay with their eggs until they hatch.

The eggs develop rapidly and hatch into larvae. Frog and toad larvae, called tadpoles, are good swimmers and eat mostly plants. Some tadpoles in temporary pools grow quickly and transform 30 — 45 days, such as American toads. Others, such as the Bullfrog tadpole, live in ponds with fish and do not transform for three years!

In fact, some bullfrogs live longer as tadpoles than they do as frogs! Salamander larvae, which eat insects, develop legs quickly so that they can walk on the bottom of the pond. When it's cold outside and they need to warm up, amphibians often bask in the sun to raise their body temperature. When it's too cold to even bask, amphibians may brumate. This means they're in a hibernation-like state, but they may have periods of wakefulness and even drink when necessary.

When it's hot outside, amphibians spend much of the time burrowing during the day, becoming active only at night. At this very moment, amphibians are facing an extinction crisis. More than species of amphibians may already be extinct. The greatest threat facing amphibians is habitat loss and degradation. Other significant threats include pollution, climate change, introduced species, and over-collection. Perhaps the most sinister threat is a newly-recognized fungal disease, which can cause rapid and severe amphibian declines.

What is being done to help amphibians? As a first step, hundreds of experts have contributed to a Global Amphibian Assessment , an ongoing project that looks at the distribution and conservation status of all known species.

In addition, amphibian specialists around the world are working on understanding the causes of the declines, developing long-term conservation programs, and responding to immediate crises. 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. To warn potential predators, the most toxic amphibians are also the most brightly colored. Curare [kyoo-RAW-ree], for example, is found on the skin of colorful poison dart frogs.

Another special feature of most amphibians is their egg-larva-adult life cycle. The larvae are aquatic and free-swimming—frogs and toads at this stage are called tadpoles. At a certain size, the young develop limbs and lungs. Although amphibians generally have the ability to breathe via their skin, that isn't their only means of breathing. Amphibians are equipped with lungs that allow them to breathe as well. On dry land, amphibians only breathe using their lungs. Amphibians also sometimes breathe through their skin when burrowing inside of soil for hibernation.

Another drawback of the especially thin skin of amphibians is heightened sensitivity. Since amphibian skin is so lean, it is especially responsive to weather swings, pollution in the air and pesticides.