The Devil Fish
Ancient sea farers were terrified of the eight armed octopus and hence its rather unfortunate nick name, the ‘devil fish’. Personally, I think the name ‘yogi fish’ would be far more fitting, due to its incredibly malleable body which allows it to squeeze through the smallest cracks and holes, with the only limit being the size of its eyeball. This makes it an extremely problematic pet for those who insist on taking it out of its natural habitat. (See the external link below for footage of a yogi fish squeezing through a one inch hole.) In fact octopuses kept as pets have been known to escape their own tank and invade neighbouring aquariums for a captive food source. This impressive flexibility is due to its lack of internal or external skeleton.
Three Hearts and a Beak
Octopuses have three hearts which live in its large head; two pump blood through each of its two gills, while the third pumps blood through the body. This also means that octopuses always have very high blood pressure. As well as three hearts these rubbery devils also have a ‘parrot-like beak’. The following passage taken from the National Wildlife Federation gives a little more elaboration:
In its den, an octopus will often simply lie hidden, its arms coiled, before unrolling one to snag a passerby with the suckers at the tip. While swimming, its preferred attack posture is to parachute gently down with all eight arms outstretched and envelop its prey in the web connecting the arms. Having wrapped up its victim, an octopus holds it against its underside and bites it with a retractable, parrot-like beak.
After scouring available video footage, I actually found film of a giant octopus lying in wait and then leaping up to kill a passing shark (see link below). When hunting a little less ambitiously, the beak can be used to drill through the shells of small crustaceans such as snails, shrimps and crabs. A toxin is then secreted to dissolve the tissues. Octopus can also ‘taste’ prey/ food with its arms, which are lined with rows of suction cups. They also have excellent eyesight. With all this overloading of sensory skills it hardly matters that they are deaf, but they also hide some additional surprising skills…
Jet Skiing on Autopilot
Most of the times I have seen an octopus has been when it is peeping out of tiny gaps underneath coral, flashing from a grey to a white colour with impressive rapidity. However, there have also been times when I have seen an octopus flinging itself from rock to rock and then freezing as if transforming itself into an inanimate object unworthy of our attention. These many different means of movement are as interesting as they are varied. As octopuses do not have full control over their arms, they simply send a high level command for movement and off they go. During this brief burst of research I also came across several accounts of octopus using their arms to ‘walk’. Of particular note were the ‘walking’ octopus marginatus, which is also known as the octopus that ‘resembles a coconut’. The report from the National Wildlife Federation explains that this “crawling arm serves as a distraction to would-be predators; this ability is also used in mating.” This leaves me wondering whether it is to distract the female or for impregnation itself? Even more intriguing are the descriptions of ‘jet propulsion’ where the octopus actually builds pressure by sealing off all orifices except a narrow funnel, and uses the thick muscles of the mantle wall to squeeze the water out the hole, allowing it to travel to speeds of up to 25 miles per hour.
Clever Devils
It comes as no surprise that octopuses are highly intelligent and reports of the ‘devil fish’ climbing on board fishing ships and opening cages of crabs/ ‘ready made meals’ remind us of why they were feared far more than most other marine life. Octopus have both a long term and short term memory which dispels the three second myth used to justify putting small fish in even smaller bowls. Unfortunately their short life span of around six months limits their learning curve, while learning from their parents is not an option as they both die shortly after copulation. It has been suggested that they also learn by doing and even through observation rather than through instinct. However, as little credit is ever given to the IQ of sea creatures this has yet to be scientifically proved. So why such a short life? With the ability to regenerate lost arms, (which may be useful since they have a tendency to eat their own arms, or even to discard them when under attack), an incredible ability to change colour and even texture, a hidden weapon of squirting ink (as a block to predators who hunt by sight or smell), their largest threat to life is the definition of a Catch 22: Reproduction is the primary cause of death!
The Ultimate Sacrifice
Males can only live for a few months after mating, while females become so preoccupied with their unhatched eggs that they rarely eat during the one month incubation period. Further research found that rather than forage for food, the primary cause of movement for the octopus is to search for its victim/ mate. When successful the experience is quite bizarre, and has been observed on many a night dive to Koh Bon: the male will extend a ‘specialized’ arm and begin to caress the female. It will then insert it into the female’s mantle cavity. Apparently at this point a sperm packet then slides slowly down a narrow groove in the arm and enters the female’s oviduct. Meanwhile, the octopuses are both flashing different colours as different pigments come into view as the cell walls are stretched or squeezed. Next time I see what I can only presume to be the suicidal male, seductively stretch out one of his eight arms to gently caress the female, trying to convince her that the price of starvation is worth the continuation of the species I’ll feel less inclined to stop my divers from photographing the ‘private’ experience. After all, it may be their last ever public showing. Meanwhile, newborn common octopuses spend the first few weeks of life invisible to divers; they have been described as ‘flealike creatures the size of rice grains’ who drift along the surface of the ocean as plankton. As they gain weight they eventually drop to the dark crevices and rocks of the bottom of the ocean.
Ultimately, what this brief research has revealed is that octopus are pretty incredible creatures, who deserve far more attention from divers such as myself, who used dismiss them as both to common and too large to warrant much excitement; let alone declarations of love. So in response to my recent octopus adoring customer I would like to say a genuine and heart-felt ‘Thank you’!
Amazing Links:
Octopus escaping through a 1 inch hole
