INTRODUCTION
The octopus traditionally, plural, octopuses is a cephalopod mollusc of the order octopods. Octopuses have two eyes and four pairs of arms, and like other cephalopods they are bilaterally systematic.
An octopus has a hard beak, with it’s mouth at the center point of the arms. Octopuses have no internal or external skeleton (although some species have a vestigial remnant of a shell inside their mantle); allowing them to squeeze through tight places. Octopuses are among the most intelligent are behaviorally flexible at all invertebrates.
The octopus inhabits many diverse region of the ocean, including coral reefs, pelagic waters, and the ocean floor. They have numerous strategies for defending themselves against predators, including the expulsion of ink, the use of camouflage and decimates displays, their ability to get quickly through the water, and their ability to hide. An octopus trails it’s eight and behind it as it swims. All octopuses are venomous, but only one group the blue-ringed octopuses is known to be deadly to humans.
There are around 300 recognized octopus species, which is over one-third of the total number of know cephalopod species. The term octopus may also be used to refer only to those creatures in the genus octopus. A group of octopuses is called a consortium.
The octopuses are characterized by their eight arms, usually bearing suction cups. The arms of octopuses are often distinguished from the pair of feeding tentacles found in squid and cuttle fish. Both types of limbs are muscular hydrostats. Unlike most other cephalopods, the majority of octopuses those in the suborder most commonly known, incirrina-have almost entirely soft bodies with no internal skeleton. They have neither a protective outer shall like the nautilus; nor any vestige at an internal shell or bones, like cuttle fish or squid. A beak, similar in shape to provide beak, is the only hard part of their body. This enables them to squeeze through very narrow slits between underwater rocks; which is very helpful when they are fleeing from morays or other predatory fish. The octopuses in the less familiar cirrina suborder have two fins and an internal shell, generally reducing their ability to squeezes into small spaces. These cirrate species are often free-swimming and live in deep-water habitats, while incirrate octopus species are found in reefs or 2 other shallow seafloor habitats.
An octopus mainly between tide pools during low tide.
Octopuses have a relatively short life expectancy and some species live for as little as six months, larger species, such as the giant pacific octopus, may live for up to five years under suitable circumstances however, reproduction is a cause of death: male can only live for a few months after mating, and female die shortly after their egg hatch. They neglect to eat during the (roughly) one month period spent taking care of their unhatched eggs, eventually drying of starvation. In a scientific experiment, it was discoverers that removal of the optic glands after spawning results in cessation of broodiness, resumption of feeding increased growth and greatly extended life-span.
CHAPTER TWO
ORIGIN OF OCTOPUS
Octopuses now found throughout the world’s dup oceans share a common origin in water around Antarctica, according to new research conducted as part of the ground breaking census if the marine life project.
This ancestral octopus species evolved in the waters ground the south pole around 33 million years ago.
It then spread outwards into new ocean basins around 15 million years ago, as the Antarctic cooled and began to develop the ice sheet that still comes it today. The pattern may prove relevant to the spread of many other kinds of marine animal. The cooling Antarctic led to what the paper’s authors cell a “thermohaline expression, a north flow of fold, nutrient-rich water with high levels of salt and oxygen, along which octopuses travelled into new habitats.
CHAPTER THREE
OCTOPUS
Scientific classification
Kingdom: Animalia
Phylum: Molusca
Class: Cephalopoda
Order: Octoprda
CHAPTER FOUR
PHYSICAL CHARACTERISTICS OF OCTOPUSES
Octopuses have three hearts. Two branched hearts pump blood through the body. Octopus blood contains the copper-rich protein hemocyanin for transporting oxygen. Although less efficient under normal conditions with low oxygen pressure, hemocyonin oxygen transportation. The hemocyanin is dissolved in the plasma instead of being carried within red blood cells and gives the glord a bluish color.
Octopuses draw water into their mantle cavity where it passes through it’s gills. As mollusks, octopuses have gills that are find divided and vascularized outgrowths of either the outer or the inner body surface.
4.1 INTELLIGENCE: Cephalopod intelligence octopuses are highly intelligent like more so then any other order of invertebrates. The exact extent of their intelligence and learning capability is much debated among biologists but maze and problem solving experiments have shown evidence of a memory system that can store both short and long term memory. It is not known precisely what contribution learning makes to adult octopus behavior young octopuses learn almost no behaviors from their parents, with whom they have very little contact.
An octopus opening a container with a screw cap. An octopus has a highly complex nervous system, only part of which is localized in its’ brain. Two – thirds of an octopus’s neurons are found in the nerve cords of it’s arms, which have limited functional autonomy.
Octopus arms show a variety of complex reflex actions that persist even when they have no input from the brain. Unlike vertebrates, the complex motor skills of octopuses are not organized in their brain using an internal somatotopic map it’s body, using a non-somatotopic system unique to large-brained invertebrates some octopus, such as the mimic octopus, will more their arms in ways that emulate the shape and movement of other sea creatures.
In laboratory experiments, octopuses can be readily trained to distinguish between different shapes and patterns they have been reported to practice.
Observational learning, although the validity of these findings is widely contested on a number of grounds. Octopuses have also been observed in what some have described as play. Repeatedly releasing bottles or toys into a circular current in their aquariums and then catching them. Octopuses often break out of their aquarium and sometimes into others in search of food. They have even boarded fishing boats and opened holds to eat crabs.
4.2 DEFENSE
An octopus’s main (primary) defense is to hide, either not to seen at all, or not to be defected as an octopus. Octopuses have several secondary defenses (defenses they use once they have been seen by a predator). The most common secondary defenses is fast escape other defenses including the use if ink sacs, camouflage, and automating limbs.
Most octopuses can eject a thick blackish ink in a large cloud to aid in escaping from predators. The main coloring agent of the ink is melanin, which is the same chemical that gives humans their hairs as skin color. This ink cloud is through to reduce the efficiency of olfactory organs, which would aid an octopus’s evasion from predators that employ smell for hunting, such as sharks. Ink clouds of some species might serve as pseudomorphs, or decoys that predator attack instead travels with shells it’s has collected for protection.
An octopuses camouflage is aided by certain specialized skin cells which can chafe the apparent color, opacity, and reflectiveness of the epidermis. Chromatophores contain yellow, orange, red, brown or black pigments. Most species have three of these color, white some have two or four, other color changing cells are reflective iridophores and leucophores (white). This color-changing ability can also be used to communicate with or warm other octopuses. The very venomous blue ringed octopus becomes bring yellow with blue rings when it is provoked. Octopuses can use muscles in the skin to change the texture of their mantle to achieve a greater camouflage. In some species the mantle can take on the spiky appearance of several, or the scraggly, bumpy texture of a rock, among other disguises. However in some species skin anatomy is limited to relatively patternless shades of one color, and limited skin texture. It is thought that octopuses that are day-active and/or live in complex habitats such as coral reefs have evolved most complex skin then their natural and/or tend dwelling relatives.
When under attack, some octopuses can perform arm autonomy, in a similar manner to the way skins, and other lizards detach their tails. The crawling arm serves as a distraction to would be predators.
A few species, such as the mimic octopus, have a fourth defense mechanism. They can combine their highly flexible bodies with their color-changing ability to accurately mimic other, more dangerous animals such as lionfish, sea snakes, and eels.
4.3 REPRODUCTION
When octopuses reproduction, makes use a specialized arm called a hectoxotylus to insert spermatophores (packets of sperm) into the female’s mantle cavity. The hectocotylus in benthic octopuses is usually the third right arm. Makes die within a few months of mating. In some specifies, the female octopus can keep the sperm alive inside her for weeks until her eggs are mature. After they have been fertilized, the female lays about 200,000 eggs.
4.4 SENSATION:
Eye of octopus vulgaris octopuses have been eyesight.
Octopuses like other cephalopods can distinguish the polarization of light. Colour vision appears to vary from species to species, being present in octopus aegina but absent in octopus vulgaris.
Attached to the brain are two special organs, called statocysts, that allow the octopus to sense the orientation of its body relative to horizontal.
An autonomic response keeps the octopus’s eye’s oriented so that the pupil slit always horizontal. Octopuses also have an excellent sense of touch. An octopus’s suction cups are equipped with chemoreceptors so that the octopus can taste what it is touching. The arms contain tension sensors so that the octopus knows whether its arms are stretched out. However, the octopus has a very poor proproceptive sense. The tension receptors are not sufficient for the octopus brain to determine the position of the octopus’s body or arms. (it is not clear that the octopus brain would be capable of processing the large amount of information that this would require, the flexibility of an octopus’s arms is much greater than that of the limbs of vertebrates, which devote large areas of cerebral cortex to the processing of propriceptive inputs). As a result, the octopus does not possess stereognosis, that is, it does not form a mental image of the overall shape of the object it is handling. It can detect local texture variations, but cannot integrate the information into a larger pictures.
The neurological autonomy of the arm means that the octopus has great difficulty learning about the detailed effects of its motions.The brain may issue a highland command to the arms, but the nerve cords in the arms execute the details. There is no neurological path for the brain to receive feedback about just how its command was executed by the arms, the only way it knows just what motions were made is by observing the arm visually. Octopuses appear to have limited hearing, octopuses swim headfirst, with arms trilling behinds.
4.5 LOCOMOTION:
Octopuses move about by crawling or swimming their main means of slow travel is crawling, with some swimming. Jet propulsion is their fastest means of locomotion, followed by swimming are walking.
They crawl by walking on their arms, usually on many at once, on both solid and soft surfaces, while supported in water. In 2005 it was reported that some octopuses (Adopus aculetus and Amphlioctopus marginatus under current taxonomy) can walk on two arms, while at the same time resembling plant matter. This form of locomotion allow these octopuses to move quickly away from a potential predator while possibly not triggering that predator’s search image for octopus food. A study of this behavior conducted by the wey mouth sea life centre led to the suggestion that the two rearmost appendages may be more accurately termed legs rather then arms. Some species of octopuses can crawl out of the water for a short period, which they may do between tide pools while hunting crustacean or gastropods or to escape predators.
Octopuses, swim by expelling a jet of water from a contractile mantel and mining it via a muscle siphon.
4.6 PREDATION
Botton-dwelling octopuses eat mainly crabs, polycheacte worms, and other molluscs such as whelks and clams. Open-oseencs octopuses eat mainly prawns, fish and other cephelopds. They usually inject their prey with a paralyzing saliva before dismembering it into small pieces with their beaks. Octopuses feed on shelled molluses either by using force, or by driving a hole in the shell, injecting a secretion into the hole, and then extracting the soft body of the mollusc.
CHAPTER FIVE
SIZE:
An adult Giant pacific octopuses enter octopus doflein, is often cited as the largest octopus species. Adult usually weigh around 15kg (331b) , with an arm span of up to 4.3m (14ft). The largest specimen of this species to be scientifically documented was an animal with live mass of 71kg (156.51b).
The alternative contender is the seven-aim octopus Haliphron altanticus, based on a 61kg (1341b) carces estimated to have a live mass of 75kg (165.1b). However, there are a number of questionable size records that would suggest. E.dofleini is the larges of all octopus species by a considerabe margin, one such record is of a specimen weighting 272 kg (600 1b) and heavy an arm span of 9m (30ft)
5.1 AS A METAPHOR
Due to having numerous arm that emanate from a common center, the octopus is often used as a metaphor for a group or organization which is perceived as being powerful, manipulative or bent on domination. Use of this terminology is invariably negative and employed by the opponents of the groups or institution so described.
5.2 AS FOOD
Human eat octopus in many cultures. The arms and sometimes other body parts are prepared in various ways, Often varying by species. Octopus is common ingredient in Japanese cuisine including Sushi, takoyaki and Akashiyaki.
In Korea, some small species are sometimes eaten alive as a novelty food. A live octopus is usually sliced up, and it is eaten while still squirming, local people catch octopuses by taking advantages of the animals habit of hiding in safe place during he night. In the evening they put grey ceramic pots on the sea bed. The morning of the following day they check them for octopuses that sheltered there. A common scene in the Greek Island is octopuses hanging in the sunlight from a rope, just like laundry from a clothesline. They are often caught by spear close to the shore. The fisherman brings his prey to land and tenderizes the flesh by pounding the carcass against a stone surface. Thus treated they are hung out to dry. And later will be served grilled either hit, or chilled in a salad. They are considered a superbmeze, especially alongside Ouzo. According to the USDA nutrient Database (2007) cooked octopus contains approximately 139 colonies per three ounce portion, and is a source of vitamin b3, b12 potassium, phosphorus and selenium, care must be taken to boil the octopuses properly to rid it at slime, smell and residual ink.
5.3 AS PET
Though octopuses can be difficult to keep in captivity, some people keep them as pets. Octopuses often escape even from supposedly secure tanks, due to their problems-solving skills, mobility and lack of rigid structure. The variation is size and life span among octopuses species makes it difficult to know how long a new specimen can naturally be expected to live. That is, a small octopus may be just born or may be an adult depending on its species. By selecting a well known species, such as the California two-spot octopuses, one can choose a small octopuses (around) the size of a tennis ball) and be confident that it is young with full life ahead of it. Large octopuses have also been known to catch and kill some species sharks.
CHAPTER SIX
CONCLUSION
Octopuses are highly intelligent more than other order of invertebrates. The exact extent of their intelligence and learning capability is much debated among biologists. It is not known precisely what contribution learning makes to adult octopus behavior young octopuses learn almost no behavior from their parents, with whom they have very little contact.
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