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10.9: Frogs and Toads

Difficulty Level: At Grade Created by: CK-12
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Frog or toad?

Although there is actually little difference between toads and frogs, this animal would most often be called a toad. Frogs have moist skin, while toads have dry, bumpy skin.

Frogs and Toads

Frogs and toads are amphibians in the order Anura. In terms of classification, there is actually not a big difference between frogs and toads. Some amphibians with leathery, bumpy skin are called "toads," but they are still in the same order as frogs.

Frogs are found in many areas of the world, from the tropics to subarctic regions, but most species are found in tropical rainforests. Consisting of more than 5,000 species (about 88% of amphibian species are frogs), they are among the most diverse groups of vertebrates. Frogs range in size from less than 0.5 inches in species in Brazil and Cuba to the 1-foot goliath frog of Cameroon.

Characteristics of Frogs

Adult frogs are characterized by long hind legs, a short body, webbed finger-like parts, and the lack of a tail ( Figure below ). They also have a three-chambered heart, as do all tetrapods except birds and mammals. Most frogs live part of the time in water and part of the time on land. They move easily on land by jumping or climbing. To become great jumpers, frogs evolved long hind legs and long ankle bones. They also have a short backbone with only 10 vertebrae. Frog and toad skin hangs loosely on the body, and skin texture can be smooth, warty, or folded.

In order to live on land and in water, frogs have three eyelid membranes: one is see-through to protect the eyes underwater, and the two other ones let them see on land. Frogs also have a tympanum , which acts like a simple ear. They are found on each side of the head. In some species, the tympanum is covered by skin.

A tree frog. Notice the powerful muscles in the limbs, and the coverings around the eyes.

How do Frogs Reproduce?

Frogs typically lay their eggs in puddles, ponds, or lakes. Their larvae, or tadpoles , have gills . Tadpoles develop into adult frogs in water ( Figure below ). You may hear males "ribbiting," producing a mating call used to attract females to the bodies of water best for mating and breeding. Frog calls can occur during the day or night.

Frogs develop from tadpoles, which develop from eggs.

How Do Frogs Eat?

Adult frogs are meat-eaters and eat mostly insects and worms. Frogs do not have teeth on their lower jaw, so they usually swallow their food whole. Some frogs have teeth on the upper jaw that are used to hold the prey in place.


  • tadpole : Larval stage of the frogs.
  • tympanum : A hearing organ in frogs.


  • Frogs are characterized by long hind legs, webbed finger-like parts, a tympanum, and the lack of a tail.
  • A frog's "ribbit" is a mating call used to attract females.


Use the resources below to answer the questions that follow.

  1. Where do rain frogs spend most of their time?
  2. How do the rain frogs mate?
  3. Why is "glue" used in rain frog mating? What problems can this cause?
  4. Why do rain frogs make their nurseries?
  5. How is the rain frog's behavior adaptive to its environment. Cite multiple examples and explain your reasoning fully.
  1. What characteristics are important to where the red-eyed tree frog lays its eggs?
  2. Compare and contrast the life cycle of a tree frog to the life cycle of a rain frog? How do the habitat differences of these frogs affect their life cycle?


  1. What are some characteristics of frogs?
  2. Why do frogs "ribbit"?




Larval stage of the frogs.


Hearing organ in frogs.

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Difficulty Level:

At Grade


7 , 8

Date Created:

Nov 29, 2012

Last Modified:

Feb 27, 2015
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