Amphibians

What are Amphibians?

Amphibians are ectothermic, tetrapod vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit various habitats, with most species living within terrestrial, fossorial, arboreal or freshwater aquatic ecosystems. All amphibians spend part of their lives in water and part on land, which is how they earned their name—“amphibian” comes from a Greek word meaning “double life.” These animals are born with gills, and while some outgrow them as they transform into adults, others retain them for their entire lives.

Types Of Amphibians

There are three types of amphibians – Anura, apoda, and urodele.

• Anura: Also called Salientia, this group primarily includes toads and frogs, making them one of the most significant orders of the class.
• Apoda: As the least familiar of orders, this group of amphibians primarily covers caecilians, which live in the ground and streams.
• Urodela: These amphibians include newts and salamanders with tails and a long yet thin body. They also have fewer bones in the skull.

Some examples of amphibians;

The species in this group include frogs, toads, salamanders, and newts. All can breathe and absorb water through their fragile skin. Amphibians also have particular skin glands that produce valuable 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 defence.

Caecilians are a group of limbless, vermiform or serpentine amphibians. They mostly live hidden in the ground and in-stream substrates, making them the least familiar order of amphibians. Caecilians are primarily distributed in the tropics of South and Central America, Africa, and southern Asia. Their diet consists of small subterranean creatures such as earthworms.

Frogs – Frogs are amphibians of the order Anura. They generally have short bodies, webbed fingers and toes, bulging eyes, and no tail. Frogs are good jumpers with long powerful legs. Toads are a type of frog. Two species of frogs are the American bullfrog and the poison dart frog. 

Salamanders – Salamanders look a bit like lizards. They have skinny bodies, short legs, and long tails. Salamanders can regrow lost limbs and other body parts. They like wet, moist areas like wetlands.

A newt is a type of salamander.

Amphibian Life Cycle

Most amphibians go through metamorphosis, a process of significant morphological change after birth. In typical amphibian development, eggs are laid in water and larvae are adapted to an aquatic lifestyle. Frogs, toads and salamanders all hatch from the egg as larvae with external gills. Metamorphosis in amphibians is regulated by thyroxine concentration in the blood, which stimulates metamorphosis, and prolactin, which counteracts thyroxine’s effect. Specific events are dependent on threshold values for different tissues. Because most embryonic development is outside the parental body, it is subject to many adaptations due to specific environmental circumstances.

For this reason, tadpoles can have horny ridges instead of Teeth, whisker-like skin extensions or fins. They also use a sensory lateral line organ similar to that of fish. However, after metamorphosis, these organs become redundant and will be reabsorbed by controlled cell death, called apoptosis.

Let’s Save Amphibians

Amphibians are the most threatened class of animals in nature. They are highly susceptible to environmental threats because of their porous eggs and semi-permeable skin. Every major threat, from climate change to pollution to disease, affects amphibians and has put them at serious risk.

Dramatic declines in amphibian populations, including population crashes and mass localized extinction, have been noted since the late 1980s from locations worldwide. Amphibian declines are thus perceived as one of the most critical threats to global biodiversity. In 2004, the International Union for Conservation of Nature (IUCN) reported stating that birds, mammals, and amphibians’ extinction rates were at minimum 48 times greater than natural extinction rates—possibly 1,024 times higher. In 2006, there were believed to be 4,035 species of amphibians that depended on the water at some stage during their life cycle. Of these, 1,356 (33.6%) were considered to be threatened. 

This figure is likely to be an underestimate because it excludes 1,427 species for which there was insufficient data to assess their status. Several causes are believed to be involved, including habitat destruction and modification, over-exploitation, pollution, introduced species, global warming, endocrine-disrupting pollutants, destruction of the ozone layer (ultraviolet radiation has shown to be incredibly damaging to the skin, eyes, and eggs of amphibians), and diseases like chytridiomycosis. However, many of the causes of amphibian declines are still poorly understood and are a topic of ongoing discussion.

Conclusion:

As we’ve discussed, we now know what amphibians are and how they live. We also got to know about how they’ll be facing endangerment these coming years, So as concerned citizens of this earth, it’s our responsibility to conserve and protect these species.