Grim
09-07-2004, 09:49
Octopuses are cephalopod mollusks characterized by having eight arms, no tentacles, and the internal shell lost or considerably reduced. There are over 100 species of octopuses (Genus Octopus) in the world as well as numerous species of deep-water and pelagic octopuses (Order Octopoda). Our knowledge of octopuses comes almost entirely from only a few species (Octopus vulgaris, O. bimaculatus, Enteroctopus dofleini, Eledone cirrhosa).
The species known as Octopus dofleini, the Giant Pacific Octopus, has recently be re-classified as Enteroctopus dofleini (Hochberg 1998). The genus Enteroctopus includes the other giant octopuses of the world (E. dofleini in the north Pacific, E. megalocyathus off S. America and E. magnificus off southern Africa).
Enteroctopus dofleini is the largest species of octopus in the world. Although it is very unusual to find an individuals over 100 pounds (45 kg), one large individual captured just near Victoria, British Columbia in 1967 weighed 156 pounds (70 kg), and was almost 23 feet (7.5 m), from arm tip to arm tip. There are records that seem to be well-referenced of a few individuals that were more than 300 pounds (136 kg) and one that was more than 400 (182 kg). (Ref: Dr. F.G. Hochberg, Santa Barbara Museum of Natural History).
Enteroctopus dofleini occurs on the continental shelf of the north Pacific ocean, where its range extends from southern California, north along the coastline of the Pacific Northwestern Americas, across the Aleutians, and south to Japan. The species occurs at depths from the intertidal to 750 m.
Enteroctopus dofleini live 3-5 years. When mature, females lay eggs on the inner side of a rocky den and may lay 20,000 to 100,000 eggs over a period of several days. Eggs are tended, cleaned and aerated by females until they hatch. Incubation takes 150 days to seven or more months, depending on the temperature. Females do not feed while tending eggs and die when the eggs hatch or shortly thereafter. Many of the eggs will die if not tended by the female until hatching.
Following hatching E. dofleini swims toward the surface and spend 4-12 weeks drifting in the plankton until they reach a size of >14 mm mantle length (still under 5 grams.). The young then settle to the bottom, although not much is known about this settlement phase.
Mature female E. dofleini have 2240 suckers, 280 on each arm, but males have fewer because there are only about 100 on the hectocoylized arm. (Toll, R. 1988. "The use of arm sucker number in octopodid systematics (Ceph.: Octopoda)" American Malacological Bulletin. 6(2):207-211. 1988). In at least shallow-water species of octopuses there seems to be a species-specific number of suckers per arm that is reached at a size less than the maximum size, with the number on the hectocotylus also species-specific. In the deep-water species, this doesn't necessarily hold.
Dens are an important resource to octopus during all benthic life stages. Dens are used both as brooding chambers and as refuges from predators, including other octopuses, various fishes, and many marine mammals. Most dens of juvenile E. dofleini are naturally occurring spaces under rocks or in crevices or are an excavated cavity in sand or gravel under a boulder.
Octopuses consume mostly crustaceans and mollusks, most often small crabs and scallops. Other bivalves, snails, fish and other octopus are also eaten.
Octopuses use three different techniques to gain entry to hard-shelled prey: they may pull it apart, bite it open with their beak or 'drill' through the shell. Prey that are difficult to pull or bite open are drilled: secretions from the salivary papilla soften the shell of the prey, and the softened material is then scraped away with the radula to create a tiny hole in the shell. Through this hole, the octopus secretes a toxin that paralyzes the prey and begins to dissolve the connective tissue. The prey is then pulled apart and consumed.
The third right arm of the male octopus is hectocotylized with a modified tip, called the ligula, that is used during mating, and in E. dofleini may be one fifth the length of the arm. Males may mate with more than one female and females receive fairly large spermatophores (up to 1m long) during mating. Eggs are laid some time after mating (one report of 42 days in captivity in Hartwick, 1983).
The mouth is located at the center of the arms. Octopuses have a strong, parrot- like beak contained within the buccal mass, the muscles which work the beak and tongue.
by cross breeding an octopus and JB, the sxoc have created a mod that can close 5 threads at once. whilst drinking a cup of tea, smoking a pipe and putting (4 pairs) of slippers
Octopuses belong to the phylum Mollusca which includes snails, clams and chitons. Their closest relatives are the chambered nautilus, cuttlefish and squids.
Octopuses have the most complex brain of the invertebrates (animals with out backbones). They have long term and short-term memories as do vertebrates. Octopuses learn to solve problems by trial-and-error and experience. Once the problem is solved, octopuses remember and are able to solve it and similar problems repeatedly.
Octopuses sense of touch is acute in it's suckers. The rim of the cups are particularly sensitive. A blindfolded octopus can differentiate between objects of various shapes and sizes as well as a sighted octopus.
When threatened, octopuses will often try to escape by releasing a cloud of purple-black ink to confuse the enemy. It's body will change color, release an ink cloud and jet away to safety. Several blotches of ink can be released before the ink sac is empty. The ink is toxic to an octopus in a confined space such as in a cave with little water current or in captivity. If the the octopus can not escape the ink (or water is not changed quickly when held in an aquarium), the octopus will become ill or perhaps die.
Many octopuses produce venomous secretions. This venom is fatal to their favorite prey - crabs and lobsters. The tiny Blue Ringed Octopus in Australia is deadly to humans. It's tiny beak can even penetrate a SCUBA diver's wet suit!
Octopuses have separate sexes (male and female) and fertilization is internal. In some species, the male can be distinguished by modified sucker discs at the tip of one of it's arms. This modified arm is used to remove a packet of sperm from within his mantle cavity and insert it into the mantle cavity of the female. Within two months after mating the female attaches strands of clustered eggs to the ceiling of her lair. The number of eggs laid by a female varies greatly depending on the species laying the eggs. The Common Octoupus, Octopus vulgaris found off the west coast of Florida may lay 200,000 - 400,000 tiny eggs. The Pygmy Octopus, Octopus joubini, lays about 150 large eggs. Once the eggs have been laid, the female octopus will gently caress the eggs with her suckers to keep algae and bacteria from growing on them. She keeps the eggs oxygenates by gently squirting them with streams of water from her syphon. After the developing octopus turns in the egg so the tip of it's mantle is at the unattached end of the egg and is ready to hatch, the female's gentle caresses become more violent to help the baby octopus escape from the egg case. Most females will not eat after laying eggs and die soon after her eggs have hatched. Some baby octopuses, like Octopus vulgaris, are carried about in water currents for about a month before they settle to the bottom. Other baby octopuses, like the large egged Octopus joubini, look like miniature adults and immediately start living their life on the bottom. Only one or two out of 200,000 eggs will survive to become adult.
The circulatory system of an octopus is closed and consists of one systemic heart, two branchial hearts, two branchial glands (gills) and blood vessels. The two branchial hearts are located at the bases of the gills and receive unoxygenated blood through the capillaries of the gills. While the blood is in the capillaries, it is reoxygenated. The two auricles of the systemic heart draw the blood from the gills and pass the blood to the median ventricle. Then the ventricle pumps oxygenated blood to all parts of the body. The blood vessels of an octopus have very thick muscular walls which help the hearts pump the blood through the capillaries.
Cephalopods are not much like us in their body plans or their lives. Many are underwater predators and are powered by high-speed jet- propulsion systems. Those that live socially communicate with each other using patterns of body colour which change so rapidly that they make our own facial expressions look sluggish.
They also have very differently organised nervous systems. They have large brains but in order to react very rapidly and control the movement of many rubbery legs (as well as controlling their body colour), a lot of information processing happens in ganglia distributed around the body. What mental powers do they have?
Recently there has been a new ripple of interest in their psychology after researchers at Naples found evidence that one octopus was capable of learning by watching what another octopus did. "Observational learning" was thought to be evidence of intelligence and restricted to the "higher" mammals and birds.
WHEN an octopus in a research laboratory in Naples learnt to choose a red ball instead of a white one by watching another octopus, students of animal learning were taken aback. Such "observational learning" is supposed to be seen only in higher vertebrates animals such as rats with sophisticated brains - Octopuses, on the other hand, are molluscs, a seemingly primitive animal group. True, octopus have huge brains. But they look nothing like the brains of the vertebrates that are so adept at learning.
The debate about observational learning in octopuses is at the centre of one of the oddest challenges in neurobiology: the quest to understand the brain of the cephalopod, animals that include octopuses, squid, cuttlefish and the single- shelled nautilus. The weird construction of the cephalopod brain was pieced together in the 1960s by J. Z. Young's classic studies of the common octopus, Octopus vulgaris. But getting to grips with how it works, and how well it works, has become fraught with disagreement.
Octopuses and squid are seductive creatures, so some critics suspect that their intelligence has been grossly exaggerated by anthropomorphising observers-"they watch my every move, therefore they must be curious". On the other hand, because cephalopod behaviour and brain structure are so foreign, others argue that their greatest cognitive feats are probably still being overlooked.
"They're very alien-an alien intelligence," says Adamo. "The way they 'think' is very different. When you consider a cat, dog or rat, we pretend we can sort of understand some of their responses. With cuttlefish, it's much more difficult."
The vertebrate central nervous system comprises one main nerve cord that has swollen at one end to create a brain. Most molluscs, on the other hand, have dual nerve cords running like a set of railway tracks along the length of the body. These are dotted with five or six pairs of ganglia, clumps of neurons that are capable of only the most primitive form of information processing. In the cephalopods alone among the molluscs, evolution has also constructed a brain. It has greatly expanded the forwardmost pairs of ganglia and moved them closer together to create a tightly packed mass of lobes that lies between the eyes and encircles the oesophagus. This is an awkward arrangement in some ways - researchers have discovered spines lodged in octopus brains, the result of a meal going down the wrong way.
"The brain is anatomically complex," says neuroscientist Ted Bullock of the University of California in San Diego. "It is very highly differentiated. It has a lot of texture, it isn't smooth or monotonous. It looks like a complicated brain, histologically and microscopically." Make no mistake, cephalopod brains cannot compare with the complexity of the brains of mammals or even birds. In brain size to body mass ratios, however, they outrank those of lower vertebrates, like reptiles and most fish.
The species known as Octopus dofleini, the Giant Pacific Octopus, has recently be re-classified as Enteroctopus dofleini (Hochberg 1998). The genus Enteroctopus includes the other giant octopuses of the world (E. dofleini in the north Pacific, E. megalocyathus off S. America and E. magnificus off southern Africa).
Enteroctopus dofleini is the largest species of octopus in the world. Although it is very unusual to find an individuals over 100 pounds (45 kg), one large individual captured just near Victoria, British Columbia in 1967 weighed 156 pounds (70 kg), and was almost 23 feet (7.5 m), from arm tip to arm tip. There are records that seem to be well-referenced of a few individuals that were more than 300 pounds (136 kg) and one that was more than 400 (182 kg). (Ref: Dr. F.G. Hochberg, Santa Barbara Museum of Natural History).
Enteroctopus dofleini occurs on the continental shelf of the north Pacific ocean, where its range extends from southern California, north along the coastline of the Pacific Northwestern Americas, across the Aleutians, and south to Japan. The species occurs at depths from the intertidal to 750 m.
Enteroctopus dofleini live 3-5 years. When mature, females lay eggs on the inner side of a rocky den and may lay 20,000 to 100,000 eggs over a period of several days. Eggs are tended, cleaned and aerated by females until they hatch. Incubation takes 150 days to seven or more months, depending on the temperature. Females do not feed while tending eggs and die when the eggs hatch or shortly thereafter. Many of the eggs will die if not tended by the female until hatching.
Following hatching E. dofleini swims toward the surface and spend 4-12 weeks drifting in the plankton until they reach a size of >14 mm mantle length (still under 5 grams.). The young then settle to the bottom, although not much is known about this settlement phase.
Mature female E. dofleini have 2240 suckers, 280 on each arm, but males have fewer because there are only about 100 on the hectocoylized arm. (Toll, R. 1988. "The use of arm sucker number in octopodid systematics (Ceph.: Octopoda)" American Malacological Bulletin. 6(2):207-211. 1988). In at least shallow-water species of octopuses there seems to be a species-specific number of suckers per arm that is reached at a size less than the maximum size, with the number on the hectocotylus also species-specific. In the deep-water species, this doesn't necessarily hold.
Dens are an important resource to octopus during all benthic life stages. Dens are used both as brooding chambers and as refuges from predators, including other octopuses, various fishes, and many marine mammals. Most dens of juvenile E. dofleini are naturally occurring spaces under rocks or in crevices or are an excavated cavity in sand or gravel under a boulder.
Octopuses consume mostly crustaceans and mollusks, most often small crabs and scallops. Other bivalves, snails, fish and other octopus are also eaten.
Octopuses use three different techniques to gain entry to hard-shelled prey: they may pull it apart, bite it open with their beak or 'drill' through the shell. Prey that are difficult to pull or bite open are drilled: secretions from the salivary papilla soften the shell of the prey, and the softened material is then scraped away with the radula to create a tiny hole in the shell. Through this hole, the octopus secretes a toxin that paralyzes the prey and begins to dissolve the connective tissue. The prey is then pulled apart and consumed.
The third right arm of the male octopus is hectocotylized with a modified tip, called the ligula, that is used during mating, and in E. dofleini may be one fifth the length of the arm. Males may mate with more than one female and females receive fairly large spermatophores (up to 1m long) during mating. Eggs are laid some time after mating (one report of 42 days in captivity in Hartwick, 1983).
The mouth is located at the center of the arms. Octopuses have a strong, parrot- like beak contained within the buccal mass, the muscles which work the beak and tongue.
by cross breeding an octopus and JB, the sxoc have created a mod that can close 5 threads at once. whilst drinking a cup of tea, smoking a pipe and putting (4 pairs) of slippers
Octopuses belong to the phylum Mollusca which includes snails, clams and chitons. Their closest relatives are the chambered nautilus, cuttlefish and squids.
Octopuses have the most complex brain of the invertebrates (animals with out backbones). They have long term and short-term memories as do vertebrates. Octopuses learn to solve problems by trial-and-error and experience. Once the problem is solved, octopuses remember and are able to solve it and similar problems repeatedly.
Octopuses sense of touch is acute in it's suckers. The rim of the cups are particularly sensitive. A blindfolded octopus can differentiate between objects of various shapes and sizes as well as a sighted octopus.
When threatened, octopuses will often try to escape by releasing a cloud of purple-black ink to confuse the enemy. It's body will change color, release an ink cloud and jet away to safety. Several blotches of ink can be released before the ink sac is empty. The ink is toxic to an octopus in a confined space such as in a cave with little water current or in captivity. If the the octopus can not escape the ink (or water is not changed quickly when held in an aquarium), the octopus will become ill or perhaps die.
Many octopuses produce venomous secretions. This venom is fatal to their favorite prey - crabs and lobsters. The tiny Blue Ringed Octopus in Australia is deadly to humans. It's tiny beak can even penetrate a SCUBA diver's wet suit!
Octopuses have separate sexes (male and female) and fertilization is internal. In some species, the male can be distinguished by modified sucker discs at the tip of one of it's arms. This modified arm is used to remove a packet of sperm from within his mantle cavity and insert it into the mantle cavity of the female. Within two months after mating the female attaches strands of clustered eggs to the ceiling of her lair. The number of eggs laid by a female varies greatly depending on the species laying the eggs. The Common Octoupus, Octopus vulgaris found off the west coast of Florida may lay 200,000 - 400,000 tiny eggs. The Pygmy Octopus, Octopus joubini, lays about 150 large eggs. Once the eggs have been laid, the female octopus will gently caress the eggs with her suckers to keep algae and bacteria from growing on them. She keeps the eggs oxygenates by gently squirting them with streams of water from her syphon. After the developing octopus turns in the egg so the tip of it's mantle is at the unattached end of the egg and is ready to hatch, the female's gentle caresses become more violent to help the baby octopus escape from the egg case. Most females will not eat after laying eggs and die soon after her eggs have hatched. Some baby octopuses, like Octopus vulgaris, are carried about in water currents for about a month before they settle to the bottom. Other baby octopuses, like the large egged Octopus joubini, look like miniature adults and immediately start living their life on the bottom. Only one or two out of 200,000 eggs will survive to become adult.
The circulatory system of an octopus is closed and consists of one systemic heart, two branchial hearts, two branchial glands (gills) and blood vessels. The two branchial hearts are located at the bases of the gills and receive unoxygenated blood through the capillaries of the gills. While the blood is in the capillaries, it is reoxygenated. The two auricles of the systemic heart draw the blood from the gills and pass the blood to the median ventricle. Then the ventricle pumps oxygenated blood to all parts of the body. The blood vessels of an octopus have very thick muscular walls which help the hearts pump the blood through the capillaries.
Cephalopods are not much like us in their body plans or their lives. Many are underwater predators and are powered by high-speed jet- propulsion systems. Those that live socially communicate with each other using patterns of body colour which change so rapidly that they make our own facial expressions look sluggish.
They also have very differently organised nervous systems. They have large brains but in order to react very rapidly and control the movement of many rubbery legs (as well as controlling their body colour), a lot of information processing happens in ganglia distributed around the body. What mental powers do they have?
Recently there has been a new ripple of interest in their psychology after researchers at Naples found evidence that one octopus was capable of learning by watching what another octopus did. "Observational learning" was thought to be evidence of intelligence and restricted to the "higher" mammals and birds.
WHEN an octopus in a research laboratory in Naples learnt to choose a red ball instead of a white one by watching another octopus, students of animal learning were taken aback. Such "observational learning" is supposed to be seen only in higher vertebrates animals such as rats with sophisticated brains - Octopuses, on the other hand, are molluscs, a seemingly primitive animal group. True, octopus have huge brains. But they look nothing like the brains of the vertebrates that are so adept at learning.
The debate about observational learning in octopuses is at the centre of one of the oddest challenges in neurobiology: the quest to understand the brain of the cephalopod, animals that include octopuses, squid, cuttlefish and the single- shelled nautilus. The weird construction of the cephalopod brain was pieced together in the 1960s by J. Z. Young's classic studies of the common octopus, Octopus vulgaris. But getting to grips with how it works, and how well it works, has become fraught with disagreement.
Octopuses and squid are seductive creatures, so some critics suspect that their intelligence has been grossly exaggerated by anthropomorphising observers-"they watch my every move, therefore they must be curious". On the other hand, because cephalopod behaviour and brain structure are so foreign, others argue that their greatest cognitive feats are probably still being overlooked.
"They're very alien-an alien intelligence," says Adamo. "The way they 'think' is very different. When you consider a cat, dog or rat, we pretend we can sort of understand some of their responses. With cuttlefish, it's much more difficult."
The vertebrate central nervous system comprises one main nerve cord that has swollen at one end to create a brain. Most molluscs, on the other hand, have dual nerve cords running like a set of railway tracks along the length of the body. These are dotted with five or six pairs of ganglia, clumps of neurons that are capable of only the most primitive form of information processing. In the cephalopods alone among the molluscs, evolution has also constructed a brain. It has greatly expanded the forwardmost pairs of ganglia and moved them closer together to create a tightly packed mass of lobes that lies between the eyes and encircles the oesophagus. This is an awkward arrangement in some ways - researchers have discovered spines lodged in octopus brains, the result of a meal going down the wrong way.
"The brain is anatomically complex," says neuroscientist Ted Bullock of the University of California in San Diego. "It is very highly differentiated. It has a lot of texture, it isn't smooth or monotonous. It looks like a complicated brain, histologically and microscopically." Make no mistake, cephalopod brains cannot compare with the complexity of the brains of mammals or even birds. In brain size to body mass ratios, however, they outrank those of lower vertebrates, like reptiles and most fish.