The axolotl "water monster", Ambystoma mexicanum, is a neotenic salamander, closely related to the Tiger Salamander. Larvae of this species fail to undergo metamorphosis, so the adults remain aquatic and gilled. It is also called ajolote (which is also a common name for different types of salamander). The species originates from numerous lakes, such as Lake Xochimilco underlying Mexico City. Axolotls are used extensively in scientific research due to their ability to regenerate limbs.
There was once eight different types of sub-species of tigers. There are currently only five sub-species left. Extinction of three different sub-species was caused by the downsize of habitat and poaching; both reasons due to humans and their carelessness, greed, and ignorance. Those three sub-species that are now no longer a part of the world are the Bali Tiger, Javan Tiger and Caspian Tiger.