With the exception of the Nautilidae and the species of octopus belonging to the suborder Cirrina , all known cephalopods have an ink sac , which can be used to expel a cloud of dark ink to confuse predators .
With the exception of the Nautilidae and the species of octopus of the suborder Cirrina , all known cephalopods have an ink sac , which can be used to push out a cloud of dark ink to confuse predators .