The Axolotl (or ajolote) (Ambystoma mexicanum) is the best-known of the Mexican neotenic mole salamaners belonging to the Tiger Salamander complex. Larvae of this species fail to undergo metamorphosis, so the adults remain aquatic and gilled. The species originates from the lake underlying Mexico City. Axolotls are used extensively in scientific research due to their ability to regenerate most body parts, ease of breeding, and large embryos. They are kept as pets in the United States, Great Britain (under the spelling Axlotl), Australia, Japan (where they are sold under the name Wooper Rooper (ウーパールーパー, Ūpā Rūpā?)), and other countries.