Los miembros de la Clase Cephalopoda son Moluscos que poseen simetría bilateral, pero cuyo pie se ha tranformado en tentáculos cefálicos y el embudo. Clase polyplacophora clase cephalopoda referencias. In general, mollusk species richness seems to be highest more than 1, species in cuba, colombia , the. En sufrió un devastador terremoto. cefalópodo Cualquier MOLUSCO marino de la clase Cephalopoda (p. ej., SEPIA, NAUTILO, PULPO y CALAMAR), .
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Cephalopodany member of the class Cephalopoda of the phylum Molluscaa small group of highly advanced and organized, exclusively marine animals.
The octopussquidcuttlefishand chambered nautilus are familiar representatives. The extinct forms outnumber the living, the class having attained great diversity in late Paleozoic and Mesozoic times. The extinct cephalopods are the ammonites, belemnites, and nautiloids, except for five living species of Nautilus.
The cephalopods agree with the rest of the Mollusca in basic structure, and the ancestors appear to have the closest affinity with the ancestors of the class Gastropoda. The best-known feature clsae the cephalopods is the possession of arms and tentacleseight or 10 in most forms but about 90 cephzlopoda Nautilus.
Except for the nautilus, all living members of the class show great modification and reduction of the characteristic molluscan shell. Cephalopods range greatly in size.
Mollusca – Wikipedia
The giant squids Architeuthis species are the largest living invertebrates; A. The smallest cephalopod is the squid Idiosepiusrarely an inch in length. The average octopus usually has arms no longer than 30 centimetres 12 inches and rarely cephlopoda than a metre 39 inches. But arm spans of up to nine metres 30 feet have been reported in Octopus dofleini.
The shell of the fossil ammonite Pachydiscus seppenradensis from the Cretaceous measures centimetres 6 feet 8 inches in diameter; it is considered to have been the largest shelled mollusk. Cephalopods occur in large numbers and form one of the greatest potential food resources of the oceans. They are cpase in most parts of the world and have been accepted as part of the general diet in North America and northern Europe.
They also are indirectly important to humans since they furnish a large part of the diet of sperm whales and smaller whales, seals, fishes, and seabirds. The sexes are usually separate in the Cephalopoda.
Sexual dimorphism is usually expressed in slight differences of size and in the proportions of various parts. In the argonaut and the blanket octopus Tremoctopus the males differ in appearance and size from the females.
The female reproductive system is simple, consisting of the posterior ovary and paired oviducts. Nidamental glands exist in species that lay eggs encased in heavy gelatinous capsules. In males the reproductive system contains a series of chambers or sacs along the course of the vas deferenswhich produce long tubes spermatophores to contain the spermatozoa.
Since spermatophores vary in appearance from species to species, they are important taxonomic characters. During courtship the male deposits spermatophores in the female, either within the mantle cavity or on a pad below the mouth, by means of a specially modified arm, the hectocotylus. The hectocotylized arm of Octopus bears a deep groove on one side, ending in a spoonlike terminal organ. In Argonauta and Tremoctopus the arm is highly modified and in mating is autotomized self-amputated and left within the mantle cavity of the female.
In the squids a much larger section of the arm may be modified; often the suckers are degenerate and the distal half of the arm bears rows of slender papillae, although special pouches and flaps may often be found. The modified arm of Nautilus is termed the spadix. Little is known about the mating habits of most cephalopods. In the common octopus the male and female remain some distance apart while the male caresses the female with the tip of the hectocotylized arm.
The male then inserts the tip of the arm into cephalopodx mantle cavity of the female, where it remains for more than an hour, during which time the spermatophores travel down the spermatophoral groove of the arm.
In the cuttlefish Sepiaaccording to the Dutch zoologist L.
Tinbergen, the pair swims side by side, the male indulging in some courtship behaviour with its arms. In loliginid squids a somewhat similar type of mating occurs, except that it takes place en masse in schools of thousands of individuals.
Eggs may be laid shortly after mating or after a prolonged period of maturation cephalopodaa which time the sperm remain viable. In loliginids they are fertilized as they are ejected and before being fixed in the egg capsule.
In the octopods they may be fertilized as they pass through oviductal glands near the end of clasw oviduct. In cuttlefishes the eggs are fertilized before the heavy capsule is formed. Egg laying in octopods is accomplished by the female individually fixing the eggs singly or in festoons by a short stalk or thread. In loliginids the eggs in fingerlike capsules often form immense moplike patches, the result of the communal spawning of perhaps hundreds of individuals.
Spawning of oceanic squids is very poorly known. The number of eggs laid during a spawning period varies greatly; cephalopodda may range from only a few dozen in octopuses with large eggs to more thanin the common octopus, laid over cephxlopoda period of about two weeks. In cuttlefishes the cephaloplda of eggs is smaller, about to being laid in a season.
In loliginids several thousand eggs may be laid by a clasf female, and the egg mop of the European common squid, resulting from the efforts of many individuals, may contain more than 40, eggs.
The eggs of most cephalopods are enclosed within a capsule that may be gelatinous and transparent the squids of the genus Loligo or opaque and leathery Octopus and cuttlefishes.
The claee of oceanic species may be laid in large sausagelike gelatinous masses or singly. The eggs of most coastal species are laid inshore and are attached singly or in clusters, primarily to rocks cephalopda shells on the bottom. Parental care is exhibited by some octopuses, in which the female broods over the eggs in the den, cephalopoad in the argonaut Argonautain which the eggs are carried in a special shell secreted by the female. In most squids and cuttlefishes the eggs are left uncared-for.
Squids that attach their eggs to the bottom engulf them in a gelatinous mass that protects them from disease and deters predators. Cuttlefishes squirt their eggs with ink when they are laid to camouflage the otherwise white eggs. All cephalopod cdphalopoda have a remarkable amount of yolkunlike that in the rest of the Mollusca, so that segmentation is incomplete and restricted to one end of the egg, where the embryo develops.
The embryo of a cuttlefish Sepiasquid Loligoor octopus Octopus has a yolk sac. In certain presumably archaic Teuthoidea there is less yolk, and the yolk sac is nearly absent. Development of the embryo cephalopods direct, without the distinctive larval stages and metamorphoses that occur in other mollusks.
Incubation time varies, but in Octopus young hatch in about 50 days and in Loligo in about 40 days. At hatching, the young may closely resemble the adult and assume the adult habitat or they may differ from the adult and spend a considerable time in the plankton as part of the drifting life.
The juveniles of many cephalopods were described as distinct genera before their juvenile status was discovered. In octopods with small eggs e. In cephalopoad with large eggs e. In the order Sepioidea cuttlefishes and bottle-tailed squids the young closely resemble the adults and are only briefly planktonic.
In the Teuthoidea squidsespecially the Oegopsida, the larvae may differ widely from the adult and the juvenile period may be quite cllase.
Little is known about the life span of cephalopods. Studies have shown that in Octopus joubini cepnalopoda from the egg in aquariums, sexual maturity and spawning were reached in five months; in a loliginid squid Sepioteuthis sepioidealikewise raised from the egg, sexual maturity and full growth were also attained in five months. It thus appears that the smaller inshore species may have a life span of no more than one year or, exceptionally, two or three. Nothing is known of the life span of the large oceanic squids, but it is presumed that giants such as Architeuthis attain their bulk only after a period of perhaps four to five years.
In the smaller octopuses and squids, observational data indicate that many of the cllase die after mating and females after the cepha,opoda major spawning.
Cephalopods are unique among the invertebrates in the degree of cephalization and cerebralization attained. The uniting of the major ganglionic centres of the central nervous system constitutes a brain of considerable complexity. Wells, and others have demonstrated that Octopus is capable of learning and has considerable intelligence. The behaviour of squids and octopuses differs considerably because of their different modes of life.
Laboratory behavioral studies have dealt mainly with learning processes and have centred around food acceptance, reward and punishment, maze work, and shape discrimination. By means of surgical techniques it has been possible to determine the various functional centres of the brain of Octopus and the transmission and receiving pathways.
In addition, field studies in tropical seas near Indonesia have recorded tool-using behaviour in the veined octopus Amphioctopus marginatus. In biologists reported having observed the animals excavating coconut half shells from the ocean floor and carrying them for use as portable shelters. Cephaloooda behaviour is regarded as the first documented example of tool use by an invertebrate. Research of a detailed nature cephaloppoda also been concerned with colour change. Most cephalopods possess colour pigment cells chromatophores and reflecting cells iridocytes in the skin.
The chromatophores are expanded by nerves controlled by the brain, and the colours are exposed brown, black, red, yellow, or orange red.
Colours and colour patterns are exhibited according to specific behavioral conditions—e. Alarm patterns are the most readily recognized, consisting of strong contrasting light and dark areas, bars and peripheral dark outlines, or vivid displays of spots, like huge eyes.
Other behavioral patterns are found in changes in skin texture, including the erection of branched or spikelike papillae and curling of the arms. These actions often are attempts by cephalopods to conceal or camouflage themselves through imitating bottom objects such as sand, coral, or seaweed.
The ink of cephalopods is used for both defense and escape. In squids the ink is ejected as a spindle-shaped mass about the size of the squid itself, the ink coagulating in the water.
Many cephalopods but not Nautilus and Octopus possess special light organs photophores cephalopoea, which emit chemical light or bioluminescence. Light is produced by the enzymatic reaction of luciferin and luciferase or, in bottle-tailed squids sepiolidsindirectly, through cultures of luminescent bacteria. Photophores distributed over the body are employed at night or in the mid depths in various ways: The light organs of the squid Histioteuthis are highly complicated, consisting of reflector, light source, directive muscles, lensdiaphragm, window, and colour screens.
Octopuses, squids, and cuttlefishes display considerable skill and cunning in hunting, stalking patiently, or luring prey within reach of their arms or tentacles. Both cuttlefishes and octopuses may use the tips of their arms as wormlike lures to attract small fishes, and octopuses have been reported to thrust stones between the valves of clams to prevent their closing.
This has not been verified by later observers, but such intelligence is not beyond belief. Cephalopods move by crawling, swimming, or jet propulsionmainly the latter. The mantlewhich has a passive role in the majority of mollusks, has become involved in locomotion in cephalopods, having almost entirely lost its rigid shell and become highly muscular. Its expansion and contraction produce a locomotory water current by drawing water into the mantle cavity and expelling it through the funnel.
The rapid ejection of this jet of water enables the animal to execute quick backward and forward movements. Water is drawn into the mantle cavity by the cephalipoda of the circular muscles and resultant expansion of the mantle. It enters around the neck region or aperture of the mantle through the funnel in some deep-sea octopuses. In the oceanic squids the system cllase more efficient, with a nonreturn valve that prevents water from entering the wrong way through the funnel.