Pardon my pedantry but:

"Although we talk of tentacles, squid specialists distinguish between true tentacles and arms. All octopuses have eight arms, which they use to crawl along the sea floor. Squids and cuttlefish also have eight arms but in addition have two much longer tentacles, which can be shot out to grab prey."

http://www.abc.net.au/science/ocean/monsters/tentacles.htm