octopuses

octopuses

Octopuses are marine mollusks of the Cephalopoda class, Octopoda order (eight feet), having eight strong, with suction cups arranged around the mouth arms. Like the rest of cephalopods, the octopus has a soft body with no internal skeleton (unlike the squid) or external, such as the Argonaut. As a means of defense, the octopus has the ability to drop paint, change its color (camouflage, through chromatophores) and autoctomy of his arms.

Octopuses have eight arms, unlike the squid and cuttlefish, which, in addition to eight arms, have two tentacles. The hectocotylus which acts at the time of reproduction is a modified arm. Since its members are used in locomotion, it can also refer to the octopus as octopuses.

All octopuses are predators and feed on fish, crustaceans and other invertebrates, hunting with arms and kill with chitinous beak. To assist hunting, octopuses developed binocular vision and eyes with a structure similar to the human organ of vision, and color perception.

Etymology

"Octopus" originated from the Greek word pól'ypous ( "of many feet"), through Latin polypu term.

Defense

An octopus hiding in a shell.

Blue-ringed octopus Hapalochlaena lunulata.
Mainly known for the ability to release an ink when fleeing, octopuses have three typical defense mechanisms: ink glands, camouflage and autoctomy arms.

Most octopuses are able to release a dense cloud of ink, to help them escape predators. The main ingredient of the ink is composed of melanin which also gives the coloring of the hair and skin of humans. The cloud of ink also has smell, being able to confuse predators like sharks that rely heavily on smell to locate prey.

The camouflage of octopi is obtained through some specialized cells of your skin and can change the apparent color and opacity of your epidermis. Chromatophores contain color pigments like yellow, orange, red, brown and black; most species have three of these pigments although some species have two or four. Another characteristic color change is achieved by changing the reflectivity iridoforas cells and leucoforas (white). The color change capability also serves to warn other octopuses on the danger of attack from a predator. The blue-ringed octopus can become an intense yellow with blue rings when provoked.

Some octopus, when threatened have autoctomy capacity of arms similarly to lizards that can release their tails. The arms released serve as distractors for predators in your hunt.

Octopuses a few species such as Thaumoctopus mimicus, have a fourth defense mechanism. They manage to combine the high flexibility of their bodies with the change of color imitating other more dangerous animals such as lionfish, snake-fish and moray eels. They are also capable of changing its texture in order to achieve a camouflage imitating stones and algae.

Reproduction

Reproduction is sexual and begins with a courtship ritual that can last several hours or days. Biologists believe that when the female is ready for fertilization it releases a pheromone that besides attractive, prevents the sexual partner the Devour (cannibalism is common in several species of octopuses). The female can be impregnated with one or more sexual partners during this period. When accepted by the female, the male octopus spermatozoa are introduced in the form of spermatophore through two specialized arms, called hectocotylus. The male octopus dies within a few months after copulation. The female, after fertilization, can store sperm for weeks until the eggs are mature. Depending on the species, the female lays eggs fertilized in a "nest" in rows or isolation that can reach up to 200 000 eggs. During maturation of the eggs, the female takes care of them, preventing algae and other organisms the attack. It also facilitates the movement of water currents so that the eggs receive sufficient oxygenation. During this period the female does not eat normally and dies shortly after the eggs hatch. After the eggs hatch, the chicks, also known as Mini-Tentacloidis, live in paralarvae phase. At that stage they feed on small animal plankton such as copepods, and larvae of crabs and starfish, seas. At this stage, part of the food chain of higher living beings as jellyfish and whales. After paralarvae stage when puppies become larger, they leave the surface of the sea, becoming adults in the bottom of the sea at low depths.

Sensory organs

Eye Octopus vulgaris
Octopuses have a good visual acuity. Despite their pupils have the line format, leading to believe that suffering from astigmatism, your vision does not seem to suffer from problems of light intensity in their habitat. It is believed that they have no color vision can distinguish although the polarization of light. Linked to the brain there are two special organs, called statocysts, which allow horizontal guidance direction. The automatic nervous system maintains the slit pupils always horizontal.

Octopuses also have a keen sense of physical touch. Their cups are equipped with chemoreceptors so that the octopus can taste the object you are touching. His arms contain tension sensors, allowing them know how much they are distentidos, although they have little sense of spatial positioning in these movements: the tension receptors are not sufficient for it to properly know the position of your arms. Being an invertebrate is unclear what the brainpower necessary to allow a correct perception of the position of his arms; the flexibility of its arms is much greater than the language of vertebrates. As a result octopuses have a weak sense to recognize the shape of the scanned objects. He can see the textures of the scanned objects but can not integrate the touch, this information in a larger object.

The neurological autonomy of his arms makes octopuses have great difficulty learning the orientation of their locomotion. There is no accuracy of these movements in both the precise positioning of his arms nor a feedback need your movements. The only way need to coordinate their movements and locomotion occurs through visual observation.

Octopuses attack when they feel threatened.

Intelligence

Cephalopods have macroneurônios that only appear in this class and are more developed than any other invertebrate.

About 1/3 of the Octopus are neurons in the brain. Theoretically these animals developed large brains due to survival needs, for example, because of the fragility of his body (no shell) where their ancentrais intelligence certainly increased the chances of escape attacks by predators, and assist in the capture with greater efficiency of the various prey varieties existing in their natural habitat.

Researchers often observe the intelligence of these animals when they are in captivity. One researcher reports having built a submarine robot that was moving in a large tank where an octopus was. The octopus is "communicated" with the robot and dismantled piece by piece. In another case, officials from the Santa Monica Pier Aquarium in California, were surprised with 750 liters of water around the ecologically constructed floor. It turns out that a curious octopus two spots had disassembled the water recycling valve and the pipe, directed out of the tank, made the water flow for 10 hours. Another unique feature is that the shellfish in them two brain areas have specialized in storage memories. It's not just the fact that they increased and condensed brain, but they also stand out for having areas in the brain dedicated to learning. It is in this aspect that resemble humans, but with a completely different brain.

Octopus fishing in Portugal

The octopus is in quantity fourth species most fished and landed in Portugal. In the period 2007-2009, the estimates for 9950 tonnes per year on average landings. If we do the analysis for total fish is next to the sardine, one of two species with the highest economic value, despite being the largest in 2008