Octopuses like to put themselves about a bit, and make the most of their eight tentacles, says John Bantin
THE COMMON OCTOPUS is found throughout the temperate and tropical marine waters of the world. It is an intelligent mollusc that has a complex eye mechanism that leads us to believe it can see very well. It can pass its boneless body through the tiniest of holes, and it has the uncanny ability to change both its colour and texture at will, by rotating tiny discs within the structure of its skin. This strategy is used primarily to avoid being detected by either prey or predator, but it's also a useful tool for communication and the expression of emotion. Never try to describe an octopus by its colour. This can range from the serene pale blue most often seen by divers at night, to an angry deep red with a white central stripe, as witnessed by divers who try to interfere with one of these remarkable creatures. During the summer months, the male octopus seeks out a female with which to mate, and so begins a courtship ritual that encompasses all his flamboyant abilities to change his appearance. He will stand erect and demonstrate his ability to become dark and knobbly. She in turn will make herself smooth and silky, often embracing herself with her own tentacles as if to appreciate her personal sensuality. Octopuses can alter their size, too. The female will grow as big as she can, inflating herself with water, while the male will try to look as non-intimidating to her as possible, often shrinking to a quarter of his normal size. In both cases, quite the opposite of human behaviour! The male specially adapts one of his tentacles to become a sexual organ, and it is this that is used to pass packets of sperm to the female. He proffers these tentatively, hoping to seduce her into accepting them. She coyly rejects him at first, while he puts on alternative displays of colour and texture in the hope of hitting on a combination that pleases her. This game can go on for a long period until he successfully persuades her and penetration ensues. The male octopus pursues the female until she catches him! Once the job is complete, she keeps hold of his tentacle and drags him off unwillingly. Is she taking him shopping? No, she's looking for a suitable home. Once she finds a suitable place to lay her eggs, she demonstrates what a dedicated mother she is. She stays with her eggs, oxygenating them regularly by blowing fresh water over them via her siphon. She stays until they are hatched, never leaving them to feed and so finally ending her own life in the process. The male escapes, however, usually leaving that specially adapted tentacle behind with her. He eventually grows a replacement, but meanwhile goes off looking for more action. You might see the occasional lucky male octopus with very few tentacles left as he cruises the reef!