Polpo - Octopus vulgaris
The Common octopus (Octopus vulgaris Cuvier, 1797) or octopus is a cephalopod mollusc of Octopodidae family, which is not to be confused with the octopus that instead it is the animal (belonging to the Cnidaria) that gives rise to the coral. Polpo Octopus vulgaris Polpo Comune cefalopode
Etymology
The term originates from the Latin octopus polypus, from a Greek Doric form πώλυπους (polypous) or πωλύπους (polypous), in the attic πολύπους (polypous), probably πολύς (polys), “very”, and πούς, (Pous ), “foot” and “by many feet.”
The term octopus comes from pieuvre, Norman dialect form derived from the Latin polypus.
Often referred to using the word octopus octopus, but the name is correct zoological octopus, as the polyps are aquatic animals (or a form thereof) belonging to the phylum Cnidaria.
Habitat and distribution
It is a cephalopod mollusk very common in shallow water, no more than 200 meters. He prefers rugged substrates, rocks, rich because of hiding places, cracks and small caves in which to hide: the absence of endo- and exoskeleton allows him to take any form, and to go through very narrow passages. Present in all the seas and oceans, it is also widespread in the Mediterranean Sea.
In the Mediterranean, it is mainly caught in two different periods of the year: from September to December (in good quantities, albeit still small) and from May to July (during which time it is more large size).
Description
The octopus has three hearts, and has the ability to change color very quickly and with great accuracy in detail. Takes advantage of this ability is to blend it to communicate with his peers. The main feature is the presence of a double row of suction cups on each of the eight tentacles, which distinguishes it from moscardino that has a single row of suction cups.
At the center of the eight tentacles, on the lower part of the animal, there is the mouth ending in a horny beak used to crack the shells shells and shells of crustaceans of which it feeds. The coat is long 8-25 cm, the tentacles instead are long on average 40-100 cm, the weight varies from 500 grams up to 7-8 kg of larger specimens.
Generally the males are larger than females. The Octopus vulgaris lives a year on average, a maximum of one year and a half. Other species such as the giant Pacific octopus (Enteroctopus dofleinii) have greater life expectancy, surviving even 5-6 years.
He can quickly move forcefully expelling water through a siphon, which is also used for the black ink discharge used for defensive purposes to confuse possible predators.
Reproduction
To attract females, octopuses performing a courtship ritual. Free sperm in seminal packages, called spermatophore. To transfer them to palleale cavity of the female during copulation, using a modified arm called ectocotilo. After the female octopus spawned (in numbers ranging from 50,000 to 400,000) defends them from possible predators until they hatch.
In this period of 1-2 months we do not eat losing a large part of its weight and die after hatching. The paralarve that come from eggs through a planktonic stage first, then undergo metamorphosis, becoming benthic, and be in all respects similar to miniature adults.
Related species
The octopus is sometimes confused with the polpessa (Octopus macropus), a cephalopod nocturnal habits, less robust and with longer tentacles of the octopus that sometimes also allow you to plunder the octopus itself, which is characterized by a reddish plumage and white dots .
Behavior
It is considered one of the most intelligent invertebrates; It was, for example, demonstrated that the common octopus has the ability to learn if subjected to tests of learning by association and by observing others of its kind, capacity that had been demonstrated only in some mammals. The latter evidence is somewhat surprising, because, as the octopus a highly solitary animal, it would seem inexplicable such behavior typical of animals with social relations.
Once caught, it is able to regain freedom exiting through the hatches of vessels. Under-test during which a prey locked in a jar was administered, the octopus has proven to be able to open the can to reach the food.
Sometimes used to crouch beneath the rocky gorges of the seabed. In other cases, he lives in burrows made with stones and shells arranged in a circle, in defense of the mouth.
Genome sequencing
In 2015, two research groups at the University of Chicago and the University of California at Berkeley, have completed sequencing the genome of the octopus and various transcriptomes, an operation which has revealed the significant peculiarities.
It is, in fact, of a larger genome than the human one and with a higher number of genes coding (approximately 33,000, 25,000 against the human genome). The vastness of the genome is due, mainly, to the expansion of two gene families, the protocaderine and the C2H2 transcription factors.
The genes coding for the protocaderine are shown in double size compared to mammals: these are proteins involved in neural development, the expansion of the family of related genes encoding gives up the extent of their neural network which, in addition to constituting the nervous system developed among invertebrates, it contains six times the number of rat neurons.
Two thirds of the octopus neurons, however, are directly connected to the organs of movement (to the point that the tentacles can perform cognitive functions even as a kind suitable: for example, a cut time are still able to recognize itself as the rest of the body).
Another peculiarity was highlighted with the identification of a group of proteins involved in the marked mimicry of the cephalopod, the reflectine, able to alter the mode of optical reflection of light impinging on the body of the octopus.
Moreover, the study of the genome has allowed the discovery of a mechanism that allows cells to quickly change the already encoded protein functions, intervening with changes on the same. Scientists speculate that this mechanism has to do with exceptional attitudes to learning exhibited by these cephalopods.
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