Amphibians are cold-blooded, they cannot regulate their own body temperature.

Amphibians spend at least part of their lives in water and on land.

Amphibians skin allows molecules and gases to pass through.

Amphibians choose to mate in or by still or static waters so the eggs they lay can remain undisturbed by water currents.

Frogs and toads- have a strong sense of location. When taken from their territories or breeding grounds, they can find their way back by smell and instinctively by the position of the stars.

Male limbed amphibians clasp the female from behind in what is called amplexus. Amphibians may remain in amplexus for hours or, in the case of frogs and toads, sometimes days. 

When the temperature drops or rises or the humidity falls, they change habitats in order to become more comfortable.

In cold or temperate regions- some amphibians go into hibernation. They seek out mud, trees, or caverns in which they remain in a state of inactivity for periods ranging from two to eight months, until the environment is again warm enough

Responding to danger- Some dive in the water or hide in dens. 

-Others pretend to be dead or camouflage themselves by changing color. -Others protect themselves with poisonous skin secretions, or puff up to look large and frightening.
Amphibians remain by water because most return to water to reproduce, and they have moist scaleless skin, only rarely living in drier environments.

Their color varies from brownish to shades of green, often with spots or blotches of a darker color around their backs. Adult bullfrogs can leap about 3 feet, but they are able to jump a distance of 6 feet without difficulty.

Males produce loud calls to attract females and establish their territories. They are aggressive when defending their territory.

2. Hellbender- The habitat of Hellbender in North America extends from southwestern and southcentral New York, west to southern Illinois, and south to extreme northeastern Mississippi.

Hellbenders inhabit large, fast-flowing, rocky streams below 2,460 ft in elevation. They grow to an adult length is about 9.4 inches to 16 inches.

An adult weighs about 3.3 lb to 5.5 lb. The breeding season begins in late August or early to mid September.
3. Andagoya Caecilian-They live in the Pacific lowlands of northwestern Colombia in the drainages of the Atrato and San Juan rivers. 

1. 
Common name- American Bullfrog
Kingdom- Animalia
Phylum- Chordata
Class- Amphibia 
Order- Anura 
Family- Ranidac
Genus- Rana
Species- catesbeiana
2.
Common name- Hellbender
Kingdom- Animalia
Phylum- Chordata
Class- Amphibia 
Order- Caudata
Family- Cryptobranchidae
Genus- Cryptobranchidae
Species- Cryptobranchidae
3.
Common name- none(Caecilia Perdita)

Kingdom- Animalia
Phylum- Chordata
Class- Amphibia 
Order-  Gymnophiona
Family- Gymnophiona
Genus- Gymnophiona
Species- perdita

Circulatory System- The circulatory system for their young and adult stages is different from each other. It resembles the circulatory system of a fish during their young phase with a two-chambered heart for pumping blood through gills to be oxygenated. After reaching adulthood, their heart becomes divided into three chambers : 1 ventricle and 2 atriums.

Digestive System- Their digestive system consists of a pancreas along with a liver and gall bladder. The liver generally has two lobes with its size depending on its function as fat and glycogen storage unit. The adipose tissue located in the abdomen is an important energy storage site. This tissue can also be found under their skin and in the tail like in certain salamanders. 
A homologous structure that can be found within the Amphibia class and Animalia kingdom is the forelimb of a frog and human. A forelimb of a frog helps the frog to elevate its body to a suitable posture for the best jump angle. Meanwhile, a human’s forelimb is used to help with balance, reach objects, and carry objects.
This shows evidence of evolution because it shows the anatomical similarities in the different species of Amphibians.