The North Pacific is the largest variety and can be 18 feet long.  
The North Pacific is the largest variety and can be 18 feet long.  Usually lacking a shell, it uses chromatophores in its skin to blend with the background.  During reproduction spermatophores are placed in the female mantle cavity by the hectocotylus, a modification of a male arm.  What cephalopod order is among the most intelligent invertebrates and, for ten points, is related to cuttlefish and squid?
The North Pacific is the largest variety and can be 18 feet long.  
octopus or Octopoda