As a defense mechanism a sea cucumber will shoot part of its resperatory system out of its body when bothered. Fish will go after the guts and give the cucumber time to scoot away and live another day.
Our dive guide poked the cucumber a bit to get us to demonstrate. Since nothing was around to eat its guts, it quickly sucked them back in. Kind of gross but fascinating, and not harmful to the sea cucumber in the end.
A very alien world down under the sea, especially at night.