Chikilidae is a brand-new species of caecilian that was recently found in Northeastern India. Further studies revealed that, the female keeps herself wrapped around her brood of eggs for 2-3 months, and that too without feeding!
The word 'amphibian' is derived from the Greek word 'amphibios', which means a double life. Amphibians are animals that can survive in water as well as land. While most species start their life underwater and move onto the land in their adulthood, there are exceptions that can survive on land during the larval stage.
Most amphibians, barring a few, have to undergo the process of metamorphosis (change in form). There are close to 7,000 species of amphibians currently in existence. There are three types of amphibians known to man, which include toads, caecilians, and salamanders. Salamanders including mud puppies and newts belong to the order Caudata. Frogs and toads belong to the order Anura, and caecilians are included in the order Apoda or Gymnophiona.
Newts and Salamanders
Many species are known to be poisonous, which is indicated through their bright and colorful skin.
These creatures are usually more active during the night, but sometimes, venture out during the day as well.
Unlike other amphibians such as frogs, they are absolutely silent and are incapable of vocalization.
They are also carnivorous and use their poison to kill small preys such as snails, insects, and worms.
While in the larval stage, the caudata develop fluffy tentacles which allow them to breathe underwater. These gill-like extensions shrink and are replaced by lungs when the creature matures.
Not all salamanders need lungs to breathe and some exist using their skin as receptors for oxygen.
Frogs and Toads
Belonging to the Anura order, toads and frogs make up for more than 90% of the entire amphibian species.
These creatures are distinct because of their large eyes, head, and strong lower limbs, which they use for leaping instead of walking.
Frogs have varied vocalization methods, and some are born with sacs under their throat which aid in amplifying their croak.
Male frogs are usually smaller and thinner than the females, which allows the males to cling to the females during mating.
These creatures lay eggs in damp soil, which either form into larvae or in some cases hatch into live young-ones.
Caecilians have eyes that are covered with a thin filament of skin. Even though this layer of skin deteriorates its vision, it does not make the creature completely blind and allows it to detect shadow and light.
Caecilians have two small tentacles at either sides of the head, which are used to detect the chemical changes in the environment.
Unlike worms, they have teeth and bones, and a very hard head which they use for borrowing.
Like other amphibians, they too have poison glands which they use for warding-off predators.
Amphibians live in various environment. However, most species of amphibians require freshwater habitats such as swamps, ponds, streams, or damp environment for breeding. Some of the frog species rely on the pools of water that is collected in the cup-shaped bases of plants or tree hollows. Many such creatures have adapted themselves to survive on trees, rocks, underground, and even in deserts!
Most amphibians have to undergo metamorphosis, wherein they transform from larva into their original adult form. For example, frogs are born with gills that allow them to survive underwater within their larval sack. However, they gradually transform and develop lungs that allow them to survive on land and breathe air.
During the process of metamorphosis, their skin develops certain glands to avoid dehydration, eardrums form, the tail disappears, and four limbs are formed which allow the frog to hop with ease.
Not all amphibians develop lungs, and yet have adapted to survive on land. Some frogs and salamanders for instance, use their skin to absorb light, heat, and oxygen. Their skin being permeable allows water to be easily absorbed, and thus ensures that these creatures remain hydrated. Since water is critical for their survival, these creatures prefer living near water bodies.
They have a soft, smooth skin, covered with moist mucus. Another peculiar characteristic of amphibians is that their permeable skin allows both gas and liquid to pass through easily. In many species of amphibians, mucus-secreting glands in the skin are modified to produce toxins that repel the predators. They also have a sticky tongue to catch and trap their prey.
Most adult amphibians possess teeth, however, in some species the teeth are scarce or totally absent. Amphibians use their teeth for holding onto their prey and not for chewing.
Many amphibians possess specialized pigment-containing cells known as chromatophores, which allow them to camouflage and blend with their environment. Many amphibians can change their skin color by dispersing or concentrating different pigments. This unique ability helps the animals adjust their body temperature and safeguard themselves against predators.
Almost all adult amphibians are carnivorous and feed on a wide variety of prey such as spiders, worms, insects, crustaceans, small reptiles, and other smaller amphibians. The salamander feeds by sucking its prey and flicks out its sticky tongue to capture them. Caecilians approach their prey slowly and kill it quickly with their sharp teeth. The frog captures prey by using its tongue which contains a glue-like substance.
Most amphibians need to be near a stagnant source of water for breeding. The eggs are placed in the water or in a damp place, so that the developing embryo does not die of dehydration. The eggs are surrounded by a protective sack that contains a clear, jellylike substance. Most amphibians lay their eggs inside the water, however, some frogs and salamanders, and all caecilians lay their eggs in moist places such as cracks or burrows in the ground, or amidst rotting leaves.
Amphibians act as crucial bio-indicators, because they aptly showcase the health of the environment they inhabit. The more the amphibians in a particular place, the healthier the place is deemed to be. However, if their population is found dwindling, it becomes a key indicator of some form of degradation, such as an increase in the toxicity of the particular habitat, pollution, or deforestation.