A gecko can drop its own tail in an instant, and the tail keeps moving after

Grabbed by a predator, many geckos snap off their own tail at a pre-set fracture point in the vertebrae, sacrificing it to escape. The severed tail keeps twitching and flipping for several minutes afterward, a decoy driven by its own local nerve activity that distracts the predator while the gecko flees. Regrowing it costs the animal weeks of stored energy, but a missing tail beats being eaten.

— Standard zoological accounts, Autotomy — Caudal autotomy in geckos and other lizards