Octopus are part of a large group of marine creatures, the Cephalopods. Their relatives include squid, cuttlefish and nautilus. The family name comes from Greek and means head-footed, a pretty self-explanatory translation. There are over 100 species including numerous deep-water and pelagic versions. The Pacific Giant Octopus is the largest, growing to about 30 feet across while way down along the family chain is the venomous blue-ringed octopus at just a few centimetres.
All octopus are soft-bodied creatures, with that huge head-body and eight long limbs, referrred to as arms, extending from it. These form a circle that encapsulates their mouth. All cephalopods have a shell of some sort – it's just not all that obvious in most – and in octopus it has reduced right down to two rods that are inside the bulbous body. These animals are incredibly entertaining underwater and have a very high level of intelligence. They can also see in much the same way that we can so will often spend a long time watching a diver. Octopus are quite hard to identify as they are all masters of camouflage, capable of changing their appearanc eat will.
One of the most incredible species – and one of the most dangerous animals in the ocean – is the blue-ringed octopus. This tiny creature uses venom as a knock-out drug. He doesn't inject it into prey but secretes a toxic salvia. Although human deaths are uncommon, the Blue-ring found in Australian waters is particularly dangerous and shoud not be handled. Most deaths have occured when unwary people pick them up!
