What are Amphibians?
The word ‘amphibian’ owes its origin to a Greek word that means ‘double life’. Amphibians generally spend the first part of their life in water and the latter part on land.
How are Amphibians classified?
Some members of this animal class are frogs, toads, salamanders, newts and caecilians.
Amphibians are four footed and have a bony skeleton with a backbone and are classified under vertebrates.
They are tetrapods (4 limbs) that facilitate moving about on land – these limbs evolved from the pectoral and pelvic fins.
The skin is thin, soft, glandular and lacks scales except in the caecilians; caecilians have skin with scales similar to those of fish.
Amphibians are ectothermic, which means they are unable to control or generate body heat and rely on external sources to moderate their body temperature.
They breathe usually with gills in the larval stage, replaced by lungs in the adult; and cutaneous(skin) respiration in many.
They have a three-chambered heart with two atria and one ventricle, a nervous system capable of perceiving pain and a well developed digestive and excretory system.
Why do Amphibian have thin and moist skin?
Most amphibians stay or grow near water. This is the reason their skin is moist and permeable. Their skin allows cutaneous respiration and the oxygen they receive this way allows it to travel directly to the bloodstream. This method of respiration is especially useful when the amphibian has to stay in burrows during unfavourable conditions or hibernation, generally during low water situation or seasonal changes.
What is the difference between Amphibian eggs and other vertebrates that lay eggs?
The eggs of amphibians are typically laid in water and hatch into free-living larvae that complete their development in water and later transform into either aquatic or terrestrial adults (metamorphosis). In many species of frog and in most lungless salamanders (Plethodontidae), direct development takes place, the larvae growing within the eggs and emerging as miniature adults.
7 Interesting facts about Amphibians
- Amphibians are a crucial link in the evolutionary chain between water dwelling fish and land dwelling vertebrates. They also have a primitive lung compared to other vertebrates, connecting them to the evolution of early vertebrates.
- The first amphibians appeared on earth more than 370 million years ago during the Devonian period.
- The Chinese giant salamander is the largest known amphibian reaching 180 cms.
- The smallest amphibian is a frog known as the Paedophryne amauensis measuring 7.7 mm.
- There are more than 6,000 species of known amphibians alive today.
- The branch of science that studies reptiles and amphibians is known as Herpetology.
- Amphibians are one of the most affected species due to water and air pollution and global warming because of their permeable skin.