Class Amphibia:

Class Amphibia is a group of cold-blooded vertebrates or chordates that includes frogs, toads, salamanders, and caecilians.

The members of class amphibia are called amphibians and it is a borderline between aquatic and terrestrial animals.

They are known for their ability to live both on land and in water.

There are also considered as the first terrestrial vertebrates.

The word "amphibia" is derived from the Greek words "amphi," which means "both," and "bios," which means "life."

Amphibias occur in almost every continent except Antarctica.Besides this,they are also absent from many oceanic islands.

Today,their three thousand species are mere remnant of this diverse group.

Body of Amphibians:

The body of amphibians is characterized by several key features:

• Moistand Permeable Skin:

Unlike other vertebrates, amphibians have a thin, permeable skin that allows for the exchange of gases, water, and electrolytes. This skin is also used for thermoregulation and protection against predators.

• Limbs:

Amphibians have four limbs, which are adapted for various functions such as swimming, jumping, and crawling. Some species, such as salamanders, have the ability to regenerate lost limbs.

• Three-Chambered Heart:

The heart of amphibians consists of three chambers – two atria and one ventricle. This arrangement allows for some separation of oxygenated and deoxygenated blood, but not as much as in mammals and birds.

• Lungs:

Most adult amphibians have lungs for breathing air on land, but some species, such as some salamanders, rely primarily on cutaneous respiration (breathing through the skin) or gills.

• Metamorphosis:

Many species of amphibians undergo a metamorphosis from an aquatic larval stage to a terrestrial adult stage. During this process, they develop lungs and limbs and lose their gills and tail.

Amphibians play an important role in many ecosystems as both predators and prey. However, many species are currently facing threats such as habitat loss, pollution, and disease.

Evolutionary History

According to fossil evidence,the members of class amphibia descended from lobe-finned lungfish about 365 million years ago. They were very successful since they were the first terrestrial vertebrates. Several of them were considerably bigger than modern-day amphibians.

The predominate group of land vertebrates for more than 100 million years was amphibians. Then some of them underwent reptilian evolution. Reptiles, which lay amniotic eggs, later superseded amphibians as the main terrestrial vertebrates on the planet.

Classification:

In general,the class amphibia can be divided into three order as given below.

° Urodela (Caudata)

•The body is elongated, with four limbs of equal size.

•The skin is smooth and covered in poison glands.

• Internal fertilisation occurs.

• They consume insects and worms. Salamanders, for example.

• They can be found in leaf litter, soil, or water.

• They primarily reproduce in the southern United States during the winter.

• There are very few differences between male and female.

• Internal fertilisation is accomplished through the use of spermatophores.

• Their gills are almost hidden.

° Anura (Salientia)

• There are approximately 3400 Anura species in the world.

• They are four-legged. To jump, the front limbs are elongated and modified.

• The head and trunk have merged.

• The tail is only present in the larval stage and is absent in adults.

• External fertilisation occurs, and eggs are laid in water.For example,in frogs and toads etc.

° Apoda (Gymnophiona or Caecilia)

• Apoda means "without legs".

• These organisms lack limbs and have scales on their bodies.

• They are also known as "blind-worms" due to the fact that their eyes are covered by skin or bone.

• The tentacles on their heads are chemosensory organs that aid in the detection of underground prey. For example Caecilians.

• They have venom glands.

• To reduce water loss, they secrete mucus.

•Role in Ecosystem:

Frogs, toads, and salamanders are examples of amphibians, which play a vital role in nature as both predators and prey. During the spring and summer, several amphibian species move to new habitats and breeding grounds, frequently at night. They help control mosquitoes, which is good for human health, and eat insect pests, which is good for agriculture.

Amphibians are remarkable indicators of ecosystem health because of how easily harmful compounds and drought can penetrate their moist, porous skin. By sustaining the fishing and logging sectors as well as recreational activities, the health of vital ecosystems, such as forests and wetlands that provide as habitat for amphibians, generates billions of dollars for the national economy.

Amphibians are a crucial component of the food chain as they serve as a source of food for a variety of creatures, including snakes and raptors.

Frequently Asked Questions-FAQs

1. What are the Characteristics of class amphibia?

Some of the basic characteristics of class amphibia are given below.

• The have ability to live in water as well as land.

• They have three chambered heart.

• They have moist and permeable skin.

2. What is it called amphibia?

The word "amphibia" is a Greek word, meaning living in double life.

Actually,the members of class amphibia acts as a borderline between aquatic and terrestrial animals. That's why, it's members are popularly known as amphibians.

Class Amphibia: Characteristics and Classification | Kingdom Animalia

Class Amphibia: