Phylum Vertebrata

Subphylum Chordata

Class Amphibia

Body Structure

frog_d2.gif The body structure of a frog is much similar to the body structure of a man. The man and the frog has the same kind of organs and system of organs. The frog body is divided into a head, short neck, and a trunk. The frog's head contains the brain, mouth, eyes, ears, and nose.
The body of an amphibians has a small waist, no neck, and a broad flat skull. The amphibians need this body shape for swimming to make it easier. The amphibians skin is thin and moist. This allows for water to exchange. The amphibians front legs and feet are short with five toes. This is used to keep the front part of the body off the ground. The amphibians eyes are positioned on the top of their head and they are large and bulging. When the eyes are positioned at the top of the head it gives the frog a wide angled vision. The large and bulging of the eye allows the frog to see under water. The amphibians ears is shaped like a flat disk-like tympanic membrane. This prevents water from entering the ear canal. Amphibians have a layer of mucus on the outer layer of skin that helps keep water on their skin.

green_and_black_poison-dart_frog.jpgObtaining Food

Tadpoles (the infant stage of a frog) are herbivores. As they grow into a frog, they evolve into carnivores. The frog mostly eats small insects and other invertebrates. Tadpoles mostly eat plants but are not totally vegetarian eaters. In the early stages they are mostly vegetarians, but towards the end of the cycle they become more carnivorous. The frog uses their long tongues to catch their prey. Their tongue shoots out of its mouth, and catches the fly or any other insect that it comes close to. A frog's tongue is actually connected the front of the mouth so that it can come out farther. The frogs and toads are a main part in the worlds ecosystem. They are also a vital link in the food change between insects and other predators. The frog can fit a lot in its mouth. Its tongue has a sticky tip that the insects stick to and it brings it back in. Tadpoles also eat water plants and adult frogs feed on land but stay near the water.


When frogs mate, the male frog tends to clasp the female underneath in an embrace called amplexus. He actually climbs on her back, reaches his arms around her waist, either just in front of the hind legs, just behind the front legs, or even around the head. Amplexus can last several days! Usually, it occurs in the water, though some species, like the bufos on the right mate on land or even in trees! For reproduction, most amphibians are fresh water bound.


strawberry_poison-dart_frog.jpg One of the amphibians like the tree frog they have sucker like sticky pads that help the frog to climb trees. Also the aquatic frog have webbing between their toes that aid them in swimming. Without the buoyancy of the water, the frogs legs have to adapt to not just the way its body moves but also to support it. The salamanders use their limbs very little in swimming. On land they use their limbs sprawled out from their body and the middle of their body usually rests on the ground. The frogs use their limbs for jumping, hopping, swimming, burrowing, and climbing. More then in the water. Frogs and toads have four fingers and five toes.
Frogs and toads also have five to ten vertebrates and no neck. Their front and back are joined together and also to of their bones and ankles. This helps the frogs leap better to get around through the forests. For little neck movement frogs have great eye vision because they can't move their neck around. Frogs that burrow into the sand to keep moist in the heat have stubby claw-like fingers that are adapted for the digging. An example of a claw-like fingered toad is the Plais Spadefoot Toad. Some frogs have parachute-like webbing on their hands and feet which act as an air-brake when they glide from tree to tree or even leaf to leaf. These types of frogs are known as "Flying Frogs."
Did you know that frogs are one of the best leapers on our planet? When frogs leap they can launch themselves 20 times their length using their big strong legs.


They were the first vertebrates to leave the water life and start a new life on land. This happened around 360 million years ago. In the desert they can only be active in a certain seasons and at certain times through out the day. This happens so they keep a regular body temperature and to not over heat. Some of the desert amphibians adapt to the surfaces like to run on,dive into, swim in or side wind across the sandy surface. Amphibian means "double life". They live in fresh water when they are first born and then live on land when they are adults. A structural adaptation is the coloring of the frog is dark on the top and lighter on the bottom so prey won't see the frog on the surface and predators won't see the frog in the water.

Importance to Humans

Amphibians are important to humans because they eat bugs. This helps us because without them our world would have way too many bugs.


tigersalamander-ambystomatigrinum.jpg Caudata (Salamanders)

This group of animals have rough skin. Also the newts are in this family.
They have a tail in the juvenile stage of their lives. The adult size of a salamander ranges from less than one inch to almost six feet.
Salamanders are usually active at night because they are nocturnal. We humans very rarely see them because during the day, they hide in moist places such as under a log!

Gulf_Coast_toad.jpgAnura (Frogs and Toads)

The anurans are the most widespread and diverse of the three extant amphibian orders. Anura means "without a tail." Adult frogs typically lay there eggs in puddles, ponds and lakes. Many frogs are able to absorb water through their skin, especially through the pelvic area. But the waterproof skin can sometimes result in water loss that is why a type of frog called the tree frogs have a waterproof layer of skin.