The Earth contains approximately 390 species of salamanders. They are a small section of the class Amphibia, which also contains frogs and caecilians. There are about 4,500 currently known species of Amphibians and the number is expected to rise to 5,000 with the current rate of discovery. The distinguishing factor separating salamanders from frogs and caecilians (the other two orders in class Amphibia) is retention of a full tail. Frogs (order Anura) lose their tail after leaving the larval stage and caecilians (order Gymnophiona) lack or only have very short tails (13). The term newt is a more restrictive type of salamander, most of which are aquatic (7). Salamanders belong to the order Caudata and are often referred to as Urodeles. Their complete taxonomic classification is as follows:
Order: Caudata (Urodela)
In form, salamanders resemble a typical lizard. The major difference is in the skin. Salamanders have smooth glandular skin with no scales. They also lack true claws and have a slightly flattened tail (13). Urodeles are extremely important scientifically because of their ability to regenerate lost limbs. They are the only vertebrates with the ability to do so as adults. Several other species of vertebrates employ autotomy, the ability to loose and regenerate the tail, as a defense mechanism. Here is a fence lizard caught in South Carolina while visiting the Savannah River Ecology Lab that shed its tail in an attempt to escape:
Photo taken by J.D. Willsion 9/30/00 (and that is my hand)
Scientists have been very interested in the regenerative capabilities of urodeles. Though they use a variety of species of salamanders and newts to run experiments, the most commonly known and used specimen is the Axolotl.
The Evolution of Regeneration in Salamanders
Back to the main page