Squid drops arms when tapped by a bottle brush. Photo by: Stephanie Bush, MBARI.

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