Define Class Cephalopoda in animal kingdom?

This group-including squids, octopuses, and the nautilus-is considered by most scientists to have the highest intelligence among all the invertebrates. They take their name from the Greek words "cephalo," meaning "head," and "poda," which means "foot." In fact, their feet have evolved into highly modified tentacles with suckers, which arise from, and are attached to, the head region. Cephalopods use these strong tentacles to capture prey. The tentacles bring the food to the mouth, where a sharp, pointed beak and a radula scrapes off the flesh. Octopuses are so named because they possess 8 tentacles. Squid have ten tentacles and the nautilus has over 80 tentacles. The length of some squid has been recorded to be in excess of 20 meters.

Although some species, like the chambered Nautilus, have kept their shells through evolution, many other species, such as octopuses and squids, have lost their shells over time. Loss of this basic form of passive protection probably led to the evolution of other characteristics, such as speedy water jet propulsion, and cryptic coloration, which is the ability to camouflage oneself by changing color to match the surroundings. Squirting out a plume of black, distasteful ink to confuse predators and mask an escape is another way cephalopods evade capture.