1. Vertebrates with Smooth, Moist Skin: Amphibians are vertebrates, meaning they have a backbone. Their skin is smooth and moist, lacking scales or feathers. This moist skin helps them breathe through their skin, a process called cutaneous respiration.
2. Metamorphosis: Amphibians undergo a significant transformation during their life cycle, a process known as metamorphosis. They start as aquatic larvae (e.g., tadpoles), breathe through gills, and have a tail. As they grow, they develop lungs, legs, and lose their tail, becoming land-dwelling adults.
3. Aquatic Larvae, Terrestrial Adults: Amphibians spend their larval stage in water, breathing through gills. However, they transform into adults that live primarily on land, though they usually stay near water sources.
4. Ectothermic (Cold-Blooded): Amphibians cannot regulate their body temperature internally. Instead, they rely on external sources of heat like the sun to warm up.
5. Lay Eggs in Water: Amphibian eggs lack shells and are laid in water or damp environments. This is because their eggs need to stay moist to prevent dehydration.
6. Three Orders: Amphibians are divided into three distinct orders:
* Anura: Frogs and toads, characterized by their short bodies, long hind legs, and the absence of tails.
* Caudata: Salamanders and newts, possessing elongated bodies and tails.
* Gymnophiona: Caecilians, legless, snake-like amphibians that are mostly subterranean.
Examples of Amphibians:
* Frogs: Bullfrog, Green Tree Frog, Poison Dart Frog
* Toads: American Toad, Cane Toad
* Salamanders: Mudpuppy, Axolotl, Red-Spotted Newt
* Caecilians: Ringed Caecilian, Blind Caecilian
By understanding these characteristics, you can readily identify and appreciate the diversity and adaptations of the amazing world of amphibians.
