Long-finned squids have a muscular bag behind the head which contains the organism's gills that provide rapid jet-propulsion used to escape predators. When the squid retracts backwards by use of the jet-propulsion, the body quickly changes to a much lighter color, and a bag of pigment opens into the mantle cavity that emits a large black cloud, confusing the predator.
- Berg, L., D. Martin, E. Solomon. 1999. Biology. Orlando, FL: Harcourt Brace College Publishers.