The octopus squid (Octopoteuthis deletron), a deep-dwelling species, has a peculiar way of escaping predators; it detaches its’ arms!
These animals are usually found deep within the Pacific Ocean and may grow up to one foot (30cm) long.
The majority of octopus and squid species (otherwise known as cephalopods) use ink as an escape strategy; when threatened, a thick cloud of ink is shot out into the water. This is used as a screening tactic so the octopus/squid can quickly escape unnoticed.
The octopus squid though, has been noted for its’ different-sized arms and it was thought that arm-dropping might be used.
After a recent study, it was proved that this was indeed a strategy used. During the study, a bottle brush was placed near the squid (imitating danger); the squid attacked in self-defense and detached two arms.
When dropped, the arms wiggle and glow (a process called bioluminescence). This confuses the predator long enough for for the squid to escape.
The arms themselves have little hooks that latch on to a would-be predator and the squid is able to detach it and leave the arm wriggling on the enemy.
Don’t worry though, because the squid can regrow their arms once they are sacrificed.
This behavior isn’t unique however, as many other animals use this strategy to avoid getting eaten; lizards lose their tails, sea stars lose their arms etc.
Want to learn more? See http://news.mongabay.com/2012/0904-santana-sacrificial-squid.html