Class amphibia|Class 11 biology|Mdcat|Chapter no 10|Kingdom Animalia

Title: Amphibians – The Dual Life Vertebrates | Biology Made Simple

Introduction: Welcome back to our channel! In today’s video, we’ll explore a fascinating group of vertebrates — the Amphibians. The name "amphibian" comes from Greek, meaning "dual life," which perfectly describes their unique lifestyle — living both in water and on land. Let’s dive in!


---

What Are Amphibians?

Amphibians belong to the Class Amphibia under the Phylum Chordata. They are cold-blooded vertebrates that typically start life in water with gills, and later develop lungs for breathing air as they grow into adults.

They are the first true land vertebrates in the evolutionary timeline, yet they are still closely tied to water — especially for reproduction.


---

Key Characteristics of Amphibians:

1. Body Structure:

Their body is bilaterally symmetrical and divided into head, trunk, and often a short tail.

The skin is moist, smooth, and glandular — without scales or hair.

Skin plays a crucial role in respiration (cutaneous respiration).



2. Limbs:

Most amphibians have two pairs of limbs adapted for jumping, walking, or swimming.

The limbs are pentadactyl (five-fingered), though in some species, the number of digits may vary.



3. Respiration:

Amphibians breathe through gills, lungs, skin, and buccal cavity at different stages of life.

Larvae usually have gills (like tadpoles), while adults use lungs and skin.



4. Circulatory System:

Amphibians have a three-chambered heart: two atria and one ventricle.

This allows double circulation, though oxygenated and deoxygenated blood mix in the ventricle.



5. Nervous System and Sense Organs:

Well-developed brain and spinal cord.

Sense organs like eyes, ears, and nostrils are present.

Eyes have eyelids, and the ears are represented by tympanic membranes (eardrums).



6. Reproduction:

Amphibians are mostly oviparous (egg-laying).

Fertilization is external in most species and occurs in water.

Eggs are jelly-like and lack shells, so they must stay moist.

They undergo external development through metamorphosis (from larva to adult).



7. Habitat:

Amphibians live in moist terrestrial or freshwater habitats.

They need water bodies for breeding and to prevent drying out.





---

Examples of Amphibians:

1. Frog (Rana tigrina) – known for jumping and croaking.


2. Toad (Bufo) – drier skin and adapted for terrestrial life.


3. Salamander (Salamandra) – retains tail and has elongated body.


4. Newts – aquatic or semi-aquatic with a lizard-like appearance.


5. Caecilians (Ichthyophis) – limbless and worm-like, mostly burrowing.




---

Importance of Amphibians:

Ecological Role: They control insect populations and serve as both predators and prey in the ecosystem.

Environmental Indicators: Their sensitive skin makes them excellent bioindicators of environmental health.

Scientific Research: Studied in genetics, development, and medicine.



---

Conclusion:

So, amphibians are an incredible group of animals bridging the gap between aquatic and terrestrial life. They are essential to both nature and science, yet many are endangered due to habitat loss and pollution.

If you found this video helpful, don’t forget to like, subscribe, and hit the bell icon for more biology lessons made simple and fun!