Facts and Characteristics of Amphibians

Amphibians are vertebrate animals, that can live in both aquatic (water) as well as terrestrial (land) environments. The name amphibian is derived from the Ancient Greek word 'amphibios' meaning living a dual life. Examples of amphibians are caecilians, frogs, toads and salamanders.

Quick Facts about Amphibians

The first amphibians came into existence in the Devonian period (416-359.2 million years ago). It is believed that amphibians evolved from fish. Here are some interesting facts about amphibians.

• The earliest frog was known to evolve about 190 million years ago, in the Jurassic period.
• Amphibians possess a three-chambered heart and most species have two lungs (except in some that have no lungs or possess reduced lungs).
• Frogs differ from toads in their habitat and skin texture. Most of their lifetime, frogs live in water and have smooth skin; whereas, toads live mostly on land and possess rough skin.
• During extreme climatic conditions, frogs enter into a resting state or dormancy, called as estivation.
• A frog in a dormant state requires very little oxygen for breathing, which is achieved through cutaneous gas exchange (breathing via skin).
• Unlike the typical amphibians that lack claws, some amphibian species like the African clawed frogs have claws.
• There are some frog species that have a baggy pouch in their pelvis for storing water in times of need.
• The Mascarene frog can leap to more than 17 feet in a single jump. Several frog species can leap to about 20 times their body length in one go.
• The Reed frog has the ability to change its sex as per the need.
• Unlike other lizards, tails of salamanders lack fracture zones. they have the ability to regenerate their limbs.
• Though female toads hardly make noise, male toads are known to be one of the noisiest amphibians.
• Most amphibians are good bio-indicators (organisms that tell something about the area they live in), as they are adapt to conditions in water as well as on land.

More than 70 percent of the frog and toad species live in the tropical rainforests. Frogs are slimy, as they tend to ooze out certain skin secretions, in order to protect themselves from drying or dehydration. Skin secretions of some frog or toad species are known to be poisonous to animals and humans. Many species of toads and frogs become very noisy, on the approach of rain and can be used as an indicator for weather change.

Characteristics of Amphibians

There are certain characteristics of amphibian species that help them to adapt in varied environmental conditions. Let's take a look at the noticeable characteristics of amphibians.

Cold-Blooded: Amphibians are cold-blooded or ectothermic animals. Unlike warm-blooded animals, which regulate their body temperature internally, amphibians derive heat from outside their body, for e.g. sunlight. Hence, the body temperature of amphibians depend upon their surroundings. They are active in warm environments and tend to become sluggish on exposure to cold temperatures.

Habitat: Amphibians start their life cycle underwater and move to land on the onset of their adulthood. They can adapt to a wide range of habitats, even man-made ones. The preferable habitats of amphibians are wet and damp areas such as wetlands, shallow ponds and marsh pools.

Nutrition: Generally, amphibians are carnivorous; while in water, they consume a wide variety of fish, small reptiles, crustaceans and other amphibians. On land, amphibians feed on worms and insects like spiders and flies. Each of the amphibian species have a different feeding habit. For e.g. frogs feed on an insect by protruding its tongue; whereas, caecilians kill their prey with the help of sharp teeth.

Breeding: Though, most amphibians breed in freshwater, there are some species that breed in moist places, like burrows in the ground and among leaf litter or in wild habitats. The eggs are covered with a clear, jellylike substance that protects them from dessication. Most amphibians undergo metamorphosis, usually accompanied with an abrupt change in habitat and behavior. In case of some frog species, the eggs hatch into tadpoles that live underwater till adulthood. Whereas, in case of other frog species, the eggs hatch directly into miniature versions of the adult frog and live in damp places.

According to recent surveys, many amphibians are said to have disappeared from areas, where they were found in abundance. In fact, some amphibians like the Poison dart frog, California tiger salamander and Houston toad are listed among the endangered species, while others are already extinct. Many biologists are of the opinion that climate change, global warming, environmental pollution and habitat loss are all playing a detrimental role in the declining population of amphibians. For e.g. the harmful UV rays of the sun affect the hatching of amphibian eggs, as they do not have protective shells. It is now high time that we conserve these wonderful amphibian creatures and contribute a bit in preserving the biodiversity of nature.