Kingdom - Animalia

Phylum - Chordata

Class - Amphibia

Orders in Illinois - Anura and Caudata

"These foul and loathsome animals are abhorrent because of their cold body, pale color, cartilaginous skeleton, filthy skin, fierce aspect, calculating eye, offensive smell, harsh voice, squalid habitation, and terrible venom; and so their Creator has not exerted his powers to make more of them."
- Carolus Linnaeus (1758)

Herpetology is the study of amphibians and reptiles. The two groups are included under a single discipline because historically, they were considered "lower forms" and not worthy of detailed investigation.

Although they share general similarities in appearance, there are important differences between the class Amphibia and the class Reptilia. In fact, reptiles are more closely related to birds and mammals than they are to amphibians!


  • have permeable skin.
  • have permeable egg membranes.
  • are constrained to moist habitats.
  • most undergo metamorphosis.


  • have scaly waterproof skin.
  • have eggs protected by a thick shell.
  • are less dependent on water.
  • do not undergo metamorphosis.

Currently recognized are over 4,500 extant (still in existence) species of amphibians divided into 41 families in 3 orders.

The three amphibian orders are: 

Anura (Frogs and Toads)

  • have a urostyle - fused vertebrae.
  • have no tail as adults.
  • have elongated ankle bones.



Caudata (Salamanders)

  • have 4 limbs of approximately equal size - except sirens
  • have tail


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Gymnophiona (Caecillians)

  • limbless
  • tails short or absent