The Cephalopods (Class Cephalopoda) include squids and octopi. They are all found in the ocean. Their name Cephalopoda means "head footed".
1) They have a series of arms or tentacles that circle the “head”.
2) Each arm has two rows of suction sups.
3) Though the octopus has eight arms, some Cephalopoda have a mixture of arms and tentacles. Some have up to a 100 tentacles!
4) Cephalopods have a relatively complex brain and eyes with good, color vision.
5) They are predators, using their arms (or tentacles) to trap prey, a sharp beak to bite prey and a central mouth to eat prey.
6) They have a funnel structure, called a hyponome, through which they can blow water to move themselves quickly along.
7) Many species have ink to release if threatened and can change color to escape predators.
8) Some cephalopods have shells to protect them, like the Nautilus while others have an internal skeletal like the squid. Octopi have neither.