An axolotl is the neotenic larva (see neoteny) of the salamander Ambystoma mexicanum. Perhaps owing to an iodine deficiency in the lakes near Mexico City where they are found, axolotls usually never become adult; but in a controlled environment they may develop into normal adult salamanders. They are 100–175 millimeters (4–7 inches) in length. The term is also applied to neotenic larvae of other salamanders.