Animal testing on amphibians

The axolotl (; from ; Ambystoma mexicanum) is a species of paedomorphic mole salamander. They mature into their terrestrial adult form without undergoing metamorphosis; the adults remain fully aquatic with obvious external gills. This trait, although somewhat unusual among the majority of amphibians, is not unique. Axolotls may be difficult to distinguish from the larval stage of other neotenic adult mole salamanders, such as mudpuppies (Necturus spp.) or the occasionally paedomorphic tiger salamander (A. tigrinum).

NASA space program which sent frogs into orbit