Meet the intelligent and gigantic octopus on Earth, giant Pacific octopus or known as North Pacific giant octopus. The size of adult giant Pacific octopus is as long as a minivan. Given scientific name Enteroctopusdofleini, this huge marine can be found at the coastal North Pacific, California, Oregon, Washington, Russia, Alaska, Japan, and Korea Peninsula. The centre of abundance appears to be in Washington. They have the ability to grow rapidly; this invertebrate can go for 100 pounds within about five years. Besides, they served a function as a host to some dicyemidmesozoans. However, the life span of this amazing animal up only to five years. Octopuses have been portrayed as scary and dangerous animals in movies such as It Came from Beneath of the Sea as a whole, yet this marine invertebrates actually shy and marmalade animal. They love to chill in the den rather than having contact with human.
Giant Pacific octopus typically found in tidal pools and up to 110m depths yet they can reside deeper than 1,500 m. They often settle down in dens or lairs, under boulders and in rock crevices. Besides, giant Pacific octopus favours to live in dens that comprises of soft substrate mud, sand or gravel and large boulders. They also can be found swaying in greater densities near kelp fields. Their metabolism depends on water temperature and ideally temperature range between 7 and 9.5 degree Celsius. Most octopuses have average weight roughly 60 kg with a dorsal mantle length of 50 cm to 60 cm. This reddish colour octopus can camouflage by changing colour and texture to its surrounding. The dorsal mantle is shaped like a sack that contains the brain, reproductive organ, digestive organ, and eyes. It has two eyes, one on each side of the head that produce acute vision and four pairs of arms that extend from the mantle. Each pair has 280 suckers comprising thousands of chemical receptors. This tentacles function as enveloping and shovelling prey into octopus’s mouth. Special receptors on their tentacles help them to taste objects and detect hidden prey just by touching them.
The extraordinary behaviour of giant Pacific octopus is that they create middens, a collection of skeleton’s prey that this invertebrate leaves in front of their den. Giant Pacific octopus is considered generalist foragers. They return to their den for feeding and deposit the remaining at the front den. The diet of this gigantic octopus consists of clams, crabs, fish, and squid. They are visual hunters that quests their prey by stalking, chasing, and camouflaging themselves with the intention to ambush prey. They have well-developed sense of vision to allow coordinating prey and trap them by using all their eggs arms. Subsequently, this cephalopod constructing different ways to consume victims such as pulling the protective shell apart to reach the meat, crushing prey by using the beak that located at the centre of its appendages and drilling a hole in the prey’s shell following injecting its toxic saliva. In contrast, this octopus avoids predation by camouflaging, hiding among kelp and staying inside their den. Juveniles often be eaten by various marine organism while adult have few predators including humans. Octopus frequently been used as a bait for Pacific halibut. As octopus is well-known with cloud of ink, they rarely used this as defences but they like to fight them with their arms and once released, they use their propulsion abilities to jet away.
The male and female giant Pacific octopus has the same rate of life span. Generally, males die a few months after mating which called a period of senescence that caused reduction of food intake, retraction of skin around the eyes, wandering and lesions that do not heal. Whereas, females live long enough to lay eggs and die afterwards as they do not feed duringbrooding period.Male reproductive organs of this invertebrate are enclosed inside the mantle cavity within a genital bag. Spermatozoa are encapsulated in a spindle-shaped spermatophoric sac. Males specialised with hectocotylized arm that used to transfer two spermatophores inside oviduct that located in the mantle of female.
Giant Pacific octopus reproduction begins with female finding male after o years to mate, reproduce and lay eggs. Mostly, during the courtship, both octopuses use their sense of sight to attract each other, male will be looking for larger female to pass their genes as larger diploid females produce more haploid eggs. In contrast, females will be searching for male with a large ligula. The ligula is a portion of the male’s hectocotylus that located at the end of his arm. It contains erectile tissue that gets bigger with temptation. Male octopus will flash intricate skin with his chromatophores to judge the readiness and willingness of female octopus to mate. Males may breed with several females but females mate only once in their lifetime.Once she finds a partner, male octopus will leave a sperm packet into the female’s mantle. The female will keep the sperm packet until she is ready to fertilize the eggs. Average for a female from mating to laying eggs is about seven months which produce between 120,000 to 400,000 eggs that looked like grape clusters. These clusters are hung at the ceiling of the den. As soon as the eggs have been laid, the female will attach them to a solid surface. She will provide and feed the fertilized eggs by blowing nutrient rich water, fanning and grooming them to remove algae and other growths. While she is nurturing her eggs, she does not move anywhere and leave their den to hunt approximately around six months of period.
Currently, giant Pacific octopus are not listed under the protection of Convention on International Trade in Endangered Species of Wild Fauna and Flora or evaluated in the IUCN Red List. Scientist depends on the numbers of catchment to evaluate the population, however, this unique marine organisms live solitarily and difficult to find. Besides, they also migrate due to food limitation, changes in water quality, increase in predation and density. Giant Pacific octopus prefers cooler oxygen-rich water as their blue blood is hemocyanin which is not an efficient oxygen carrier. As an intelligent invertebrate, they have been kept commonly on display at aquariums as they can open tank valves, dissemble equipment and capable of motor play. In addition, by using its 300 million neurons, they can successfully solve simple puzzles.