Scientists have discovered the largest species that has the ability to regrow limbs. According to Business Insider, it's the alligator. Like lizards, young American gators can regrow their tails up to 9 inches. Prof. Kenro Kusumi is a co-senior study author and the director of Arizona State University's School of Life Sciences. Kusumi began studying gator regrowth after receiving a package in the mail that contained a deformed alligator tail in a pickle jar with ethanol. The tail was discolored, forked, and the scales were smaller than normal. Kusumi realized that the tail looked like it had been regrown.