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Phylum: Annelida. Class: Polychaeta Grube, Groups included. Palpata · Scolecida · Cladistically included but traditionally excluded taxa. Chaetopteridae. The Polychaeta /ˌpɒlɪˈkiːtə/, also known as the bristle worms or polychaetes, are a. Annelida. Class: Clitellata. Order: Oligochaeta. Family: Naididae. Subfamily: Tubificinae. Genus: Tubifex. Lamarck, Tubifexjpg. Tubifex is a cosmopolitan genus of tubificid annelids that inhabits the sediments of lakes, rivers. PENGERTIAN KLASIFIKASI ANNELIDA 1. Polychaeta Polychaeta (dalam bahasa yunani, poly = banyak, chaetae = rambut kaku) merupakan.

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Each body segment has a pair anneliida fleshy protrusions called parapodia that bear many bristles, called chaetaewhich are made of chitin. As such, polychaetes are sometimes referred to as bristle worms. More than 10, species are described in this class. Common representatives include the lugworm Arenicola marina and the sandworm or clam worm Alitta.

Polychaetes as a class are robust and widespread, with species that live in the coldest ocean temperatures of the abyssal plainto forms which tolerate the extremely klaslfikasi temperatures near hydrothermal vents.

Polychaetes occur throughout the Earth’s oceans at all annelixa, from forms that live as plankton near the surface, to a 2- to 3-cm specimen still unclassified observed by the robot ocean probe Nereus at the bottom of the Challenger Deepthe deepest known spot annleida the Earth’s oceans. They can sometimes be brightly coloured, and may be iridescent or even luminescent. Each segment bears a pair of paddle-like and highly vascularized parapodiawhich are used for movement and, in many species, act as the worm’s primary respiratory surfaces.

Bundles of bristles, called setaeproject from the parapodia. However, klasicikasi vary widely from this generalised pattern, and can display a range of different body forms. The most generalised polychaetes are those that crawl along the bottom, but others have adapted to many different ecological nichesincluding burrowing, swimming, pelagic life, tube-dwelling or boring, commensalismand parasitismrequiring various modifications to their body structures. The head, or prostomiumis klasifiaksi well developed, compared with other annelids.

It projects forward over the mouth, which therefore lies on the animal’s underside.

klasifikasi annelida – Site Title

The head normally includes two to four pair of eyes, although some species are blind. These are typically fairly simple structures, capable of distinguishing only light and dark, although some species have large eyes with lenses that may be capable of more sophisticated vision. The head also includes a pair of antennaetentacle-like palpsand a pair of pits lined with cilia klssifikasi, known as “nuchal organs”.

These latter appear to be chemoreceptorsand help the worm to seek out food. The outer surface of the body wall consists klxsifikasi a simple columnar epithelium covered by a thin cuticle. Underneath this, in order, are a thin layer of connective annlida, a mlasifikasi of circular muscle, a layer of longitudinal muscle, and a peritoneum surrounding the body cavity.

Additional oblique muscles move the parapodia. In most species the body cavity is divided into separate compartments by sheets of peritoneum between each segment, but in some species it’s more continuous.

Annslida mouth of polychaetes is located on the peristomiumthe segment behind the prostomiumand varies in form depending on their diets, since the group includes predators, herbivores, filter feeders, scavengers, and parasites. In general, however, they possess a pair of jaws and a pharynx that can be rapidly everted, allowing the worms to grab food and pull it into their mouths.


In some species, the pharynx is modified into a lengthy proboscis. The digestive tract is a simple tube, usually with a stomach part way along. The smallest species, and those adapted to burrowing, lack gillsbreathing only through their body surfaces. Most other species have external gills, often associated with the parapodia. A simple but well-developed circulatory system is usually present. The two main blood vessels furnish smaller vessels to supply the parapodia and the gut.

Blood flows forward in the dorsal vessel, above the gut, and returns down the body in klasifilasi ventral vessel, beneath the gut. The blood vessels themselves are contractile, kpasifikasi to push the blood along, so most species have no need of a heart.

In a few cases, however, muscular pumps analogous to a heart are found in various parts of the system. Conversely, some species have little or no circulatory system at all, transporting oxygen in the coelomic fluid that fills their body cavities. The blood may be colourless, or have any of three different respiratory pigments.

Tubifex – Wikipedia

The most common of these is haemoglobinbut some groups have haemerythrin or the green-coloured chlorocruorin klasifikasu, instead. The nervous annnelida consists of a klasfiikasi or double ventral nerve cord running the length of the body, with ganglia and a series of small nerves in each segment.

The brain is relatively large, compared with that of other annelids, and lies in the upper part of the head. An endocrine gland is attached annelidda the ventral posterior surface of the brain, and appears to be involved in reproductive activity.

In addition to the sensory organs on the head, photosensitive eye spots, statocystsand numerous additional sensory nerve endings, most likely in involved with the sense of touch, also occur on the body.

Polychaetes have a varying number of protonephridia or metanephridia for excreting waste, which in some cases can be relatively complex in structure. The body also contains greenish “chloragogen” tissue, similar to that found in oligochaeteswhich appears to function in metabolism, in a similar fashion to that of the vertebrate liver.

Their jaws are formed from sclerotised collagen, and their setae from sclerotised chitin. Polychaetes are extremely variable in both form and lifestyle, and include a few taxa that swim among the plankton or above the abyssal plain.

Most burrow or build tubes in the sediment, and some live as commensals. A few are parasitic. The mobile forms Errantia tend to have well-developed sense organs and jaws, while the stationary forms Sedentaria lack them, but may have specialized gills or tentacles used for respiration and deposit or filter feeding, e.

Underwater polychaetes have eversible mouthparts used to capture prey. Some have even evolved cutaneous invaginations for aerial gas exchange. Most polychaetes have separate sexes, rather than being hermaphroditic.

The most primitive species have a pair of gonads in every segment, but most species exhibit some degree of specialisation. The gonads shed immature gametes directly into the body cavity, where they complete their development. Once mature, the gametes are shed into the surrounding water through ducts or openings that vary between species, or in some cases by the complete rupture of the body wall and subsequent death of the adult.

A few species copulatebut most fertilize their eggs externally. The fertilized eggs typically hatch into trochophore larvae, which float among the planktonand eventually metamorphose into the adult form by adding segments. A few species have no larval form, with the egg annelidz into a form resembling the adult, and in many that do have larvae, the trochophore never feeds, surviving off the yolk that remains from the egg.


Some polychaetes exhibit remarkable reproductive strategies. Some species in the genus Eunicie reproduce by epitoky. For much of the year, these worms look anneliida any other burrow-dwelling polychaete, but as the breeding season approaches, the worm undergoes a remarkable transformation as new, specialized segments begin to grow from its klasifi,asi end until the worm can be clearly divided into two halves.

The front half, the atoke, is asexual.

The new rear half, responsible for breeding, is known as the epitoke. Each of the epitoke segments is packed with eggs and sperm and features a single eyespot on its surface. The beginning of the last lunar quarter is the cue for these animals to breed, and the epitokes break free from the atokes and float to the surface.

klasifikasi annelida

The eye spots sense when the epitoke reaches the surface and the segments from millions of worms burst, releasing their eggs and sperm into the water. Another strange strategy is employed by the deep sea worm Syllis ramosa which lives inside a sponge. The rear end of the worm develops into a “stolon” containing the eggs or sperm, and this stolon becomes detached from the parent worm, and rises to the sea surface where fertilisation takes place.

Wiwaxialong interpreted as an annelid, [12] is now considered to represent a mollusc. Being soft-bodied organismsthe fossil record of polychaetes is dominated by their fossilized jaws, known as scolecodontsand the mineralized tubes that some of them secrete.

Polychaete cuticle does have some preservation potential; it tends to survive for at least 30 days after a polychaete’s death. Taxonomically, polychaetes are thought to be paraphyletic[18] meaning the group excludes some descendants of its most recent common ancestor. Groups that may be descended from the polychaetes include the oligochaetes earthworms and leechessipunculansand echiurans.

The Pogonophora and Vestimentifera were once considered separate phyla, but are now classified in the polychaete family Siboglinidae.

Older classifications recognize many more sub orders than the layout presented here. As comparatively few polychaete taxa have been subject to cladistic analysis, some groups which are usually considered invalid today may eventually be reinstated. From Wikipedia, the free encyclopedia. List of Annelid families. Freshwater Animal Diversity Assessment: Retrieved 12 February An Encyclopedia of Curious and Unusual Animals. Retrieved 9 August Implications for the ancestral molluscan radula”.

Proceedings of the Royal Society B. Estonian Journal of Earth Sciences. Journal of Natural History. Retrieved from ” https: Paraphyletic groups Polychaetes Extant Cambrian first appearances. Views Read Edit View history.

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