Making the world better, one answer at a time. Octopuses and squids can also move by using a form of jet propulsion. Water is drawn into the mantle cavity and then forced out through a tube, propelling the cephalopods backwards from danger. In addition, squids and octopuses produce a dark-colored ink when the are frightened.
http://www.answers.com/Q/How_do_squids_escape_its_predator
Most cephalopods rely on vision to detect predators and prey, and to communicate with one another. Consequently, cephalopod vision is acute: training experiments have shown that the common octopus can distinguish the brightness, size, shape, and horizontal or vertical orientation of objects.
https://en.wikipedia.org/wiki/Cephalopod
In the Coleoidea, the molluscan shell has been internalized or is absent, whereas in the Nautiloidea, the external shell remains. About 800 living species of cephalopods have been identified. Two important extinct taxa are the Ammonoidea (ammonites) and Belemnoidea (belemnites).
https://en.wikipedia.org/wiki/Cephalopod
Cephalopods are the only mollusks with a closed circulatory system. Coleoids have two gill hearts (also known as branchial hearts) that move blood through the capillaries of the gills. A single systemic heart then pumps the oxygenated blood through the rest of the body.
https://en.wikipedia.org/wiki/Cephalopod
Lay the squid with its head to the left and its siphon up. See Fig. 6-13. 2. Reach under the animal and remove the pen from the dorsal side by grasping it firmly with your fingers and pulling it free from the mantle. 3. Using scissors cut the mantle from its anterior edge next to the siphon to its posterior tip.
http://www.edhsgreensea.net/Biology/biopdfs/SQUID_LAB.pdf
In the mouth of the squid is a beak shaped much like the beak of a parrot. The beak is not part of the shell but a separate tooth-like structure. When a squid catches prey, such as a fish, it bites off and swallows chunks of it. The squid has a small radula but it uses it only to pull in chunks of food past the beak. masters of camouflage, using pigment in their skin cells to quickly change its skin color to blend into its surroundings. These skin cells, called chro-matophores, contain an elastic sac filled with pigment.
http://www.edhsgreensea.net/Biology/biopdfs/SQUID_LAB.pdf
They can also squirt ink from the ink sac into the water, creating an ink cloud for camouflage and confusing the predator. The squid and cuttlefish can also wave their paddle-shaped fins to move slowly forward or backward. The fins also aid the squid in steering and in stabilizing their movements.
http://www.edhsgreensea.net/Biology/biopdfs/SQUID_LAB.pdf
They don't. Most bivalves shells protect them from predators, but some become prey to the more intelligent or even more brute animals of the sea. The exception to this is the … scallop, which can actually propel itself by opening and closing its shell with enough force to fly away from danger.
http://www.answers.com/Q/How_do_squids_escape_its_predator
The nervous system of cephalopods is the most complex of the invertebrates and their brain-to-body-mass ratio falls between that of endothermic and ectothermic vertebrates. The brain is protected in a cartilaginous cranium.
https://en.wikipedia.org/wiki/Cephalopod
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. This sac is a muscular bag which originated as an extension of the hind gut.
https://en.wikipedia.org/wiki/Cephalopod
what are several methods of escape used by cephalopods
Cephalopods have an ink sac, which can be used to expel a cloud of dark ink to confuse predators.