1. Amphibians
Soaiba, Roanna & Rodas

2. External Physical Amphibians are divided into 3 groups:
Anura- lack tails and have long hind legs; well adapted for jumping and swimming. (Ex. frogs and toads)
Urodela- have long tails and small, undeveloped legs. (Ex. newts and salamanders)
Gymnophiona- are blind, legless amphibians shaped like worms.
Amphibians have muscular tongues. Their skin contains many mucous glands, and in some species, poison glands.

3. Circulatory System
In amphibians, blood flow is directed in two circuits
pulmonary circulation: it carries blood through the lungs and back to the heart for obtaining oxygen
2. Systemic circulation: and this one carries blood throughout the rest of the body and its organs, including the brain
Amphibians are a little different from a
From a fish, instead of the two
Chambered hearts, they have three
(Two atria and one ventricle)
Two atria receive deoxygenated blood
From both circuits (lungs and the systems)
The ventricle mixes blood, which reduces
The efficiency of oxygenation (diagram)

4. Reproduction
Amphibians reproduce sexually with either internal or external fertilization.
Every species have a different way of calling mates. Different frog species croak loudly distinctively to call their specific mate of the same species.
Salamanders use their sense of smell to find their mates. The male salamanders also produce a smell that attract the females of their species.
Amphibians must lay their eggs in water otherwise the eggs will dry out. Most amphibians are done parenting after they’ve mated and laid their eggs.

5. Respiration
Amphibians have a specialized method of breathing through their skin called cutaneous respiration.
Cutaneous respiration is a form of respiration, in which gas exchange occurs across the skin in organisms rather than gills or lungs.
Aquatic amphibians rely primarily on cutaneous respiration, like the hellbender salamander.
In air, where oxygen is more concentrated, some small species can rely solely on cutaneous gas exchange, most famously the plethodontid salamanders, which have neither lungs nor gills.

6. Excretion
Excretion is the process of excreting (removing) waste from the body
The excretion system of an amphibian starts with taking in liquid waste from the kidneys. Which removes wastes and extra water to become urine, which then is collected in the urinary bladder through the ureters. The urinary bladder is present ventral to the rectum and both open into the cloaca.

7. Nervous System
Amphibians have the same nervous systems as other vertebrates. Amphibians have a central brain, a spinal cord, and nerves throughout the body.
The Amphibian brain consists of a cerebrum, a midbrain and a cerebellum. The cerebrum is a combination of the amphibians behaviour and learning(memory, voluntary muscle control). They also have an olfactory lobe that is the center of their sense of smell. The cerebellum is the center of muscle coordination. They also have optic lobes of the brain that associate with vision. The brain sends signals through the spinal cord and nerves to the rest of the body.

8. Feeding & Digestion
Most frog larvae are herbivores, whereas salamander larvae are carnivores. However, adult frogs and salamanders are predators and feed on small invertebrates.
After an amphibian eats, the food flows from its mouth to its esophagus to its stomach. Digestion begins in the stomach of an amphibian. Food then moves to the small intestine, where enzymes from the pancreas start the digestion process.
From the small intestine, nutrients from the food are absorbed into the bloodstream and delivered to body cells. Food moves from the small intestine to the large intestine before waste is eliminated. Digestive waste enters the cloaca before it exits the body.

9. Movement
Amphibians are born with a tail, some grow up and grow out of the tail eg. frogs and some keep it eg.salamanders.
The most common way amphibians move is by crawling hopping and walking on land with their four legs.
Many amphibians have legs, but they are very weak. The reason they have such weak legs is to help the animal move well both on land and in water