Animal kingdom | Part -5

Characteristics and Examples of Amphibians

Amphibians are a fascinating group of animals that bridge the gap between aquatic and terrestrial life. Belonging to the class Amphibia, they exhibit a wide range of adaptations that allow them to thrive both in water and on land. Amphibians are cold-blooded vertebrates and are among the earliest vertebrates to have adapted to a semi-terrestrial lifestyle.

Key Characteristics of Amphibians

• Dual Life (Amphibious Nature): The word "amphibian" means "dual life," indicating their ability to live both in water and on land during different life stages.
• Skin: Their skin is moist, smooth, and permeable, enabling respiration through the skin (cutaneous respiration) along with lungs and gills.
• Respiration: Larval stages breathe through gills, while adults usually use lungs and skin for respiration.
• Reproduction: Most amphibians lay eggs in water. Fertilization is usually external, and development involves a larval stage (e.g., tadpole).
• Cold-Blooded: Amphibians are ectothermic, meaning their body temperature varies with the environment.
• Circulatory System: They have a three-chambered heart (two atria and one ventricle).
• Movement: They usually have four limbs (tetrapods) used for walking, jumping, or swimming.
• Metamorphosis: Amphibians undergo metamorphosis — a transformation from aquatic larvae to terrestrial adults.

Examples of Amphibians

• Frog (e.g., Rana tigrina): Commonly found in moist environments, frogs are excellent jumpers and swimmers.
• Toad (e.g., Bufo): Toads have dry, warty skin and are better adapted to life on land compared to frogs.
• Salamander (e.g., Ambystoma): Salamanders have elongated bodies and tails, and they retain some larval traits as adults (neoteny).
• Caecilian (e.g., Ichthyophis): These are limbless, burrowing amphibians that resemble worms or snakes.

Amphibians play an essential role in maintaining ecological balance by controlling insect populations and serving as food for other animals. Due to their sensitivity to environmental changes, they are also important indicators of ecosystem health.