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, they usually
never become adult; but in a controlled environment they may develop into
normal adult salamanders. They are 100–175mm (4–7in) in length.
The term is also applied to neotenic larvae of other salamanders.