Oligochaeta feeding level-Oligochaeta - Wikipedia

Megadriles are robust terrestrial earthworms. Microdriles are small, thin bodied aquatic worms. Identification of Oligochaeta to generic and species level usually involves internal anatomy, particularly the genital system, rather than external features. Some Tubificinae species can withstand low oxygen tensions, and are often found in large numbers in organically polluted rivers. Kambolgie Creek, Kakadu NP NT Ecology : Microdriles occur in both running and still waters including, oligotrophic lakes and streams, organically enriched wetlands, and groundwater.

Oligochaeta feeding level

Oligochaeta feeding level

All rights reserved. Earthworms are found in all parts of the world except for deserts. Functional Feeding Group : gathering collectors. Updated: October 09, The vascular system consists of two main vessels connected by lateral vessels in each segment. In other projects Wikimedia Commons Oligochaeta feeding level.

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The copulating pair exchange sperm, which are stored in the body of the recipient worm until its Oligochaeta feeding level are mature. Soil Biology Guide. Numerous soil scientists have been equally fascinated by the amount of work done by them, Charles Darwin said of them "It may be doubted whether there many Oligochaeta feeding level animals which have played so important a part in the history of the world as these lowly organised creatures". These are located in the dorsal side of the alimentary canal in the third segment, in a groove between the buccal cavity and pharynx. The fertilized eggs are deposited in a cocoon, secreted by the clitellum; the cocoon is buried in mud or affixed to submerged objects. Oligochaeta feeding level are found worldwide, and inhabit terrestrial, freshwater, and marine ecosystems. In this species asexual reproduction but budding from the posterior end feedinv throughout the Oligochafta and can produce chains of individual worms still attached to each other. Order Myzostomida Body disk-shaped or oval without external segmentation; external or internal commensals or parasites Guilt after sex echinoderms, especially crinoids; size, minute to 1 cm; genera include Myzostoma. Soils have a definite worm carrying capacity which relates directly to the amount of organic matter in, and regularly added to, them yearly in natural environments. The mating pair overlap front ends ventrally and each exchanges sperm with the other. The ovaries are found in segments 13 and the oviduct opens on segment Article Media.

Sources Brusca, R.

  • The subclass Oligochaeta contains all the animals commonly thought of as 'earthworms'.
  • Updated: October 09,
  • Oligochaete classification relies largely on internal structures, especially the arrangement and number of gonads, the position of the gonoducts, and particularly the location of the male pore.

This class includes about 3, species of earthworms and freshwater worms. Oligochaetes occur in a variety of habitats throughout the world. Other species live under rocks on the seashore, in the leaves of tropical trees and vines, on the surface of glaciers, or on the gills of freshwater crayfish. Like the polychaetes, oligochaetes have bodies divided into segments. However, they lack parapodia and, with a few exceptions, have relatively few and inconspicuous setae.

The setae are usually arranged in four bundles on each segment; those of aquatic forms are longer than those of land forms. The setae of an earthworm may be felt as a roughness if one rubs a finger along its side. As many as 4, oligochaetes have been counted in 1 square meter of lake bottom, and about 9, in 1 square meter of meadow soil. Light is detected by photoreceptor cells in the skin, usually concentrated toward the front of the animal.

The mouth, located under the head, leads to a relatively simple, straight digestive tract consisting of a pharynx, an esophagus, and an intestine, terminating in an anal opening.

Terrestrial oligochaetes tunnel through the ground, swallowing soil as they go. The digestive tract of such a worm is specially modified for this rough diet. Typically it has a thin-walled storage area, or crop, and a muscular gizzard for grinding the soil to remove the organic matter that is the actual food of the worm.

Specialized calciferous glands remove excess calcium, magnesium, strontium, and phosphate and regulate the level of these ions in the blood. Solid wastes are egested and plastered against the burrow wall, or ejected from the mouth of the burrow; the ejected material is called castings. Earthworms, through their burrowing and digestive processes, are largely responsible for the mixing and aeration of the soil. Not all oligochaetes have soil diets; some of the small aquatic worms are active predators on other small invertebrates.

Excretion is typically carried out by a pair of tubes in each segment. The circulatory system is that typical of the annelids and has many contractile vessels, or hearts.

Oxygen dissolved in the soil water diffuses through the moist epidermis of the worm. If earthworms are forced to the surface, as when their burrows are filled with rainwater, they suffocate as a result of desiccation. All oligochaetes are hermaphroditic, and nearly all cross-fertilize by copulation. Male and female reproductive organs are located in separate segments.

The copulating pair exchange sperm, which are stored in the body of the recipient worm until its eggs are mature. The worm then secretes a cocoon into which it deposits the eggs and the sperm; fertilization and development of the eggs occur in the cocoon. When the young emerge they are miniatures of the adults. The cocoon is secreted by a glandular region, the clitellum, consisting of several thickened segments.

The clitellum of an earthworm is a conspicuous saddle-shaped region near its front end. The Columbia Electronic Encyclopedia, 6th ed. All rights reserved. Enter your search terms:. Oligochaete Anatomy Like the polychaetes, oligochaetes have bodies divided into segments. Oligochaete Digestion The mouth, located under the head, leads to a relatively simple, straight digestive tract consisting of a pharynx, an esophagus, and an intestine, terminating in an anal opening.

Oligochaete Circulation and Respiration The circulatory system is that typical of the annelids and has many contractile vessels, or hearts. Oligochaete Reproduction All oligochaetes are hermaphroditic, and nearly all cross-fertilize by copulation.

Oligochaetes occur in a variety of habitats throughout the world. The setae of some polychaetes, e. Soils have a definite worm carrying capacity which relates directly to the amount of organic matter in, and regularly added to, them yearly in natural environments. Specialized calciferous glands remove excess calcium, magnesium, strontium, and phosphate and regulate the level of these ions in the blood. Roberts; Frances M Hickman European Journal of Soil Biology. Once through the gizzard, food continues through the intestine for digestion.

Oligochaeta feeding level

Oligochaeta feeding level

Oligochaeta feeding level. Distinguishing taxonomic features

The blood system is a closed system, meaning that they have blood vessels through which the blood flows. There are two main longitudinal blood vessels, a dorsal one and a ventral one, as well as three smaller longitudinal vessels, two lateral neural vessels and one sub-neural vessel. These vessels have circular muscles around them which can contract rhythmically to keep the blood moving around the body. The vessels also contain valves which ensure the blood only flows in one direction. Blood flows from the head to the tail in the ventral vessel and back, from the tail to the head, in the dorsal vessel.

In each segment a number of smaller lateral side vessels branch off from the main vessels to supply the sections of that segment. The blood of annelids contains haemoglobin, the same respiratory pigment as in humans, it is this that makes their blood the same red colour as ours.

Gaseous exchange normally occurs over the whole of the animal's body. Becausegaseouss exchange is far greater in the presence of moisture terrestrial species, secrete moisture in the form of coelomic fluid from the dorsal pores, mucous from the epidermal mucous glands and the excretions of the nephridia. Excretion of metabolic wastes is through the action of nephridia. These are long coiled tubes which have many cilia lining their internal surface.

Both blood and coelomic fluid enter these nephridia where nutrients, water and salts are removed before the remaining wastes are passed out through the nephridiopore. Oligochaetes are hermaphrodites, with separate testis and ovaries. The sexual organs, and the ducts that lead to and from them are situated in the anterior front part of the animal, normally between segments 7 and The actual placement of the reproductive organs, including the openings of the ducts, which are normally on the same segments are important in classification.

In Lumbricuscus terrestris , a common worm in Western Europe, the testis are in segments 10 and 11, the seminal vesicles in segments 9,11, and 12, while the vas deferens opens on segment The ovaries are found in segments 13 and the oviduct opens on segment The sexual organs and their ducts are paired, one on each side of the worms body. Sperm travels from the opening of the vas deferens to the clitellum, segments , along two seminal grooves. Copulation occurs on warm damp nights.

The worms lie head to tail and side by side. In this way the clitellum segments of each animal are opposite the segments containing the sexual organs of the other. The clitella secrete a mucous tube that surrounds the worm from before the first reproductive segment to the clitella segments segments 8 to 36 in L.

Sperm received from the partner worm is stored in the spermathecal openings segment 9 in L. Each worm now secretes a new mucous tube, one that is enriched with albumin from the clitellum and wrapped in membranene. The eggs 5 - 16 in L. Fertilisation occurs inside the cocoon. The cocoon is left under the ground, or attached to plants under the water and often changes shape, becoming darker, smaller and harder. The exact detail vary from species to species but the general pattern remains the same.

The Oligochaeta are a diverse group of organisms, although they are fairly similar in basic design. The taxonomic description of the group varies depending on which expert you talk with. If Clitellata is a class then Oligochaeta is normally a subclass, but Clitellata can be a Superclass in some classification schemes and thus Oligochaeta becomes a class in its own right.

These sorts of problems abound through the whole living world and you shouldn't worry about them, until you know enough to actually participate in the arguments it is best to use a generalised, even if possibly out of date scheme such as this, or whatever other the scheme your teacher or lecturer proposes.

If any Oligochaeta taxonomists stumble across this could you please Email me a better scheme at g. They possess gills for gaseous exchange which are situated on the inside of their anus. Naidids live in a variety of manners. They can be filter feeders, such as Ripestes parasita , carnivorous hunters such as Chaetogaster limnaei or substrate eaters mud in this case such as members of the genera Aulophorus and Dero.

Chaetogaster limnaei lives in the pulmonary cavity of water snails where it feeds on the larvae of parasitic Platyhelminths flukes that attach the snail.

Some Naidids such as Stylaria lacustris can reproduce both asexual and sexually. In this species asexual reproduction but budding from the posterior end occurs throughout the summer and can produce chains of individual worms still attached to each other. In the autumn however it turns into a normally sexual organisms. The family Tubificidae are a group of worms that live in mud where they feed on the organic matter trapped in the mud.

They are commonly referred to as tubifex worms. Tubificids are red because they have a blood pigment that is very like haemoglobin. Living in the mud that lines the floor of many aquatic habitats the secrete thin tubes to live in. They spend their time with their heads down in the mud and their tails up in the water.

They beat their tails to drive a current of water down into their tubes and over their bodies. However there are exception such as Branchiura sowerbyi which has long delicate gills rising from its posterior end. They achieve this by taking slightly longer strides but with slightly lower stride frequencies. This causes the writhing movements observed when a human picks up an earthworm. This behaviour is a reflex and does not require the CNS; it occurs even if the nerve cord is removed.

Each segment of the earthworm has its own nerve plexus. The plexus of one segment is not connected directly to that of adjacent segments. The nerve cord is required to connect the nervous systems of the segments. The giant axons carry the fastest signals along the nerve cord.

These are emergency signals that initiate reflex escape behaviours. The larger dorsal giant axon conducts signals the fastest, from the rear to the front of the animal. If the rear of the worm is touched, a signal is rapidly sent forwards causing the longitudinal muscles in each segment to contract. This causes the worm to shorten very quickly as an attempt to escape from a predator or other potential threat. The two medial giant axons connect with each other and send signals from the front to the rear.

Stimulation of these causes the earthworm to very quickly retreat perhaps contracting into its burrow to escape a bird. The presence of a nervous system is essential for an animal to be able to experience nociception or pain. However, other physiological capacities are also required such as opioid sensitivity and central modulation of responses by analgesics. This indicates that opioid substances play a role in sensory modulation, similar to that found in many vertebrates. Earthworms do not have eyes although some worms do , however, they do have specialized photosensitive cells called "light cells of Hess".

These photoreceptor cells have a central intracellular cavity phaosome filled with microvilli. As well as the microvilli, there are several sensory cilia in the phaosome which are structurally independent of the microvilli. A relatively small number occur on the ventral surface of the 1st segment.

The gut of the earthworm is a straight tube which extends from the worm's mouth to its anus. It is differentiated into a alimentary canal and associated glands which are embedded in the wall of the alimentary canal itself.

The alimentary canal consists of a mouth, buccal cavity generally running through the first one or two segments of the earthworm , pharynx running generally about four segments in length , esophagus, crop, gizzard usually and intestine. Food enters in the mouth.

The pharynx acts as a suction pump; its muscular walls draw in food. In the pharynx, the pharyngeal glands secrete mucus. Food moves into the esophagus, where calcium from the blood and ingested from previous meals is pumped in to maintain proper blood calcium levels in the blood and food pH.

From there the food passes into the crop and gizzard. In the gizzard, strong muscular contractions grind the food with the help of mineral particles ingested along with the food. Once through the gizzard, food continues through the intestine for digestion. The intestine secretes Pepsin to digest proteins, Amylase to digest polysaccharides, Cellulase to digest cellulose, and lipase to digest fats.

The intestine has its own pair of muscle layers like the body, but in reverse order—an inner circular layer within an outer longitudinal layer. Earthworm have a dual circulatory system in which both the coelomic fluid and a closed circulatory system carry the food, waste, and respiratory gases. The closed circulatory system has five main blood vessels: the dorsal top vessel, which runs above the digestive tract; the ventral bottom vessel, which runs below the digestive tract; the subneural vessel, which runs below the ventral nerve cord; and two lateroneural vessels on either side of the nerve cord.

The dorsal vessel is mainly a collecting structure in the intestinal region. It receives a pair commissural and dorsal intestinals in each segment. The ventral vessel branches off to a pair of ventro-tegumentaries and ventro-intestinals in each segment. The subneural vessel also gives out a pair of commissurals running along the posterior surface of the septum. The pumping action on the dorsal vessel moves the blood forward, while the other four longitudinal vessels carry the blood rearward.

In segments seven through eleven, a pair of aortic arches rings the coelom and acts as hearts, pumping the blood to the ventral vessel that acts as the aorta. The blood consists of ameboid cells and hemoglobin dissolved in the plasma. The second circulatory system derives from the cells of the digestive system that line the coelom. As the digestive cells become full, they release non-living cells of fat into the fluid-filled coelom, where they float freely but can pass through the walls separating each segment, moving food to other parts and assist in wound healing.

The excretory system contains a pair of nephridia in every segment, except for the first three and the last ones. The integumentary nephridia lie attached to the inner side of the body wall in all segments except the first two. The septal nephridia are attached to both sides of the septa behind the 15th segment. The pharyngeal nephridia are attached to fourth, fifth and sixth segments. From there it is carried through the septum wall via a tube which forms a series of loops entwined by blood capillaries that also transfer waste into the tubule of the nephrostome.

The excretory wastes are then finally discharged through a pore on the worm's side. Earthworms have no special respiratory organs.

Gases are exchanged through the moist skin and capillaries, where the oxygen is picked up by the hemoglobin dissolved in the blood plasma and carbon dioxide is released. Water, as well as salts, can also be moved through the skin by active transport.

At birth, earthworms emerge small but fully formed, only lacking their sex structures which develop in about 60 to 90 days. They attain full size in about one year.

Among lumbricid earthworms, parthenogenesis arose from sexual relatives many times. Earthworms are hermaphrodites ; that is, they have both male and female sexual organs. The sexual organs are located in segments 9 to Earthworms have one or two pairs of testes contained within sacs. The two or four pairs of seminal vesicles produce, store and release the sperm via the male pores.

Ovaries and oviducts in segment 13 release eggs via female pores on segment 14, while sperm is expelled from segment As a result, segment 15 of one worm exudes sperm into segments 9 and 10 with its storage vesicles of its mate.

Some species use external spermatophores for sperm transfer. In Hormogaster samnitica and Hormogaster elisae transcriptome DNA libraries were sequenced and two sex pheromones , Attractin and Temptin, were detected in all tissue samples of both species.

Outcrossing would provide the benefit of masking the expression of deleterious recessive mutations in progeny. Copulation and reproduction are separate processes in earthworms.

The mating pair overlap front ends ventrally and each exchanges sperm with the other. The clitellum becomes very reddish to pinkish in color. Some time after copulation, long after the worms have separated, the clitellum behind the spermathecae secretes material which forms a ring around the worm.

The worm then backs out of the ring, and as it does so, it injects its own eggs and the other worm's sperm into it. As the worm slips out of the ring, the ends of the cocoon seal to form a vaguely onion-shaped incubator cocoon in which the embryonic worms develop.

Earthworms travel underground by the means of waves of muscular contractions which alternately shorten and lengthen the body peristalsis. The shortened part is anchored to the surrounding soil by tiny claw-like bristles setae set along its segmented length.

In all the body segments except the first, last and clitellum, there is a ring of S-shaped setae embedded in the epidermal pit of each segment perichaetine.

The whole burrowing process is aided by the secretion of lubricating mucus. Worms can make gurgling noises underground when disturbed as a result of their movement through their lubricated tunnels. Earthworms move through soil by expanding crevices with force; when forces are measured according to body weight, hatchlings can push times their own body weight whereas large adults can push only 10 times their own body weight.

Earthworms have the ability to regenerate lost segments, but this ability varies between species and depends on the extent of the damage. Stephenson devoted a chapter of his monograph to this topic, while G. An unidentified Tasmanian earthworm shown growing a replacement head has been reported. Within the world of taxonomy, the stable 'Classical System' of Michaelsen and Stephenson was gradually eroded by the controversy over how to classify earthworms, such that Fender and McKey-Fender went so far as to say, "The family-level classification of the megascolecid earthworms is in chaos.

Categorization of a megadrile earthworm into one of its taxonomic families under suborders Lumbricina and Moniligastrida is based on such features as the makeup of the clitellum, the location and disposition of the sex features pores, prostatic glands, etc.

The families, with their known distributions or origins: [38]. From a total of around 7, species, only about species are widely distributed around the world. These are the peregrine or cosmopolitan earthworms. Earthworms are classified into three main ecophysiological categories: 1 leaf litter- or compost-dwelling worms that are nonburrowing, live at soil-litter interface and eat decomposing organic matter called Epigeic e.

Lumbricus terrestris. Earthworm populations depend on both physical and chemical properties of the soil, such as temperature, moisture, pH, salts, aeration , and texture, as well as available food, and the ability of the species to reproduce and disperse. Lumbricus terrestris is still present in a pH of 5.

Soil pH may also influence the numbers of worms that go into diapause. Earthworms are preyed upon by many species of birds e. Earthworms have many internal parasites , including protozoa , platyhelminthes , and nematodes ; they can be found in the worms' blood , seminal vesicles , coelom , or intestine , or in their cocoons.

Nitrogenous fertilizers tend to create acidic conditions , which are fatal to the worms, and dead specimens are often found on the surface following the application of substances such as DDT , lime sulphur , and lead arsenate. In Australia , changes in farming practices such as the application of superphosphates on pastures and a switch from pastoral farming to arable farming had a devastating effect on populations of the giant Gippsland earthworm , leading to their classification as a protected species.

Vermicomposting of all organic "wastes" and addition of this organic matter, preferably as a surface mulch , on a regular basis will provide earthworms with their food and nutrient requirements, and will create the optimum conditions of temperature and moisture that will naturally stimulate their activity.

This earthworm activity aerates and mixes the soil, and is conducive to mineralization of nutrients and their uptake by vegetation. Certain species of earthworm come to the surface and graze on the higher concentrations of organic matter present there, mixing it with the mineral soil.

Because a high level of organic matter mixing is associated with soil fertility , an abundance of earthworms is generally considered beneficial by farmers and gardeners. Also, while, as the name suggests, the main habitat of earthworms is in soil, they are not restricted to this habitat.

The brandling worm Eisenia fetida lives in decaying plant matter and manure.

Identification and Ecology of Australian Freshwater Invertebrates

Haplotaxida Lumbriculida Moniligastrida. Specifically, the oligochaetae contain the terrestrial megadrile earthworms some of which are semiaquatic or fully aquatic , and freshwater or semiterrestrial microdrile forms, including the tubificids , pot worms and ice worms Enchytraeidae , blackworms Lumbriculidae and several interstitial marine worms. With around 10, known species, the Oligochaeta make up about half of the phylum Annelida. These worms usually have few setae chaetae or "bristles" on their outer body surfaces, and lack parapodia , unlike polychaeta.

They range in length from less than 0. Terrestrial oligochaetes are commonly known as earthworms and burrow into the soil.

The four main families with large numbers of species are Glossoscolecidae , Lumbricidae , Megascolecidae and Moniligastridae. Earthworms are found in all parts of the world except for deserts.

They have a requirement for moist surroundings and the larger species create burrows that may go down several metres yards while young individuals and smaller species are restricted to the top few centimetres of soil.

The largest numbers are found in humus-rich soils and acid soils. A few species are found in trees, among damp moss and in the debris that accumulates in leaf axils and crevices; some others make their homes in the rosettes of bromeliads.

The majority of aquatic oligochaetes are small, slender worms, whose organs can be seen through the transparent body wall. Some are transitional between terrestrial and aquatic habitats, inhabiting swamps, mud or the borders of water bodies. The first segment, or prostomium , of oligochaetes is usually a smooth lobe or cone without sensory organs, although it is sometimes extended to form a tentacle.

The remaining segments have no appendages, but they do have a small number of bristles, or chaetae. These tend to be longer in aquatic forms than in the burrowing earthworms, and can have a variety of shapes. Each segment has four bundles of chaetae, with two on the underside, and the others on the sides. The bundles can contain one to 25 chaetae, and include muscles to pull them in and out of the body.

This enables the worm to gain a grip on the soil or mud as it burrows into the substrate. When burrowing, the body moves peristaltically , alternately contracting and stretching to push itself forward. A number of segments in the forward part of the body are modified by the presence of numerous secretory glands.

Together, they form the clitellum , which is important in reproduction. The digestive tract is essentially a tube running the length of the body, but has a powerful muscular pharynx immediately behind the mouth cavity.

In many species, the pharynx simply helps the worm suck in food, but in many aquatic species, it can be turned inside out and placed over food like a suction cup before being pulled back in. The remainder of the digestive tract may include a crop for storage of food, and a gizzard for grinding it up, although these are not present in all species. The oesophagus includes "calciferous glands" that maintain calcium balance by excreting indigestible calcium carbonate into the gut.

A number of yellowish chloragogen cells surround the intestine and the dorsal blood vessel, forming a tissue that functions in a similar fashion to the vertebrate liver. Some of these cells also float freely in the body cavity, where they are referred to as "eleocytes". The few exceptions generally have simple, filamentous gills. Excretion is through small ducts known as metanephridia. Terrestrial oligochaetes secrete urea , but the aquatic forms typically secrete ammonia , which dissolves rapidly into the water.

The vascular system consists of two main vessels connected by lateral vessels in each segment. Blood is carried forward in the dorsal vessel in the upper part of the body and back through the ventral vessel underneath , before passing into a sinus surrounding the intestine.

Some of the smaller vessels are muscular, effectively forming hearts; from one to five pairs of such hearts is typical. The blood of oligochaetes contains haemoglobin in all but the smallest of species, which have no need of respiratory pigments.

The nervous system consists of two ventral nerve cords, which are usually fused into a single structure, and three or four pairs of smaller nerves per body segment. Only a few aquatic oligochaetes have eyes, and even then they are only simply ocelli. Nonetheless, their skin has several individual photoreceptors, allowing the worm to sense the presence of light, and burrow away from it.

Oligochaetes occur in every continent in the world occupying terrestrial, freshwater and marine habitats. Of the known aquatic species, about are marine and inhabit groundwater. Movement and burrowing of earthworms is performed by peristalsis , with the alternation of contraction and relaxation of the circular and longitudinal muscles.

To move forward, the anterior portion of the worm is extended forward by the contraction of the circular muscles, while the portion just behind this is made shorter and fatter by the contraction of longitudinal muscles. Next the anterior circular muscles relax, and a wave of circular contraction moves backwards along the worm. The worm is able to reverse its direction of travel with the tail leading.

Aquatic species use a similar means of locomotion to work their way through sediment and massed vegetation, but the tiny Aeolosomatids swim by means of the cilia on their prostomia.

Burrowing is performed by forcing the front end of the worm into a crevice and widening the gap by body expansion. Large quantities of soil are swallowed in the process. This is mixed with mucus as it passes through the gut, being used to plaster the tunnel walls, forming a lining. Excess material is extruded on the ground surface, forming a faecal casting. The burrow may have two entrances and several vertical and horizontal tunnels.

Whereas in general, polychaetes are marine and have separate sexes, external sperm transfer and external fertilisation, oligochaetes live on land or in fresh water, are hermaphrodites , have no external sperm transfer and fertilisation takes place in the clitellum or cocoon. However there are exceptions to this, with some polychaetes inhabiting non-marine environments and a few species of oligochaetes being marine.

Reproduction among oligochaetes is mainly by sexual means but clonal reproduction is common in some genera, especially among aquatic species. Members of the Naididae reproduce asexually , primarily by paratomy , in which the body breaks into two pieces after the "pregeneration" of certain anterior structures by the posterior portion.

Other species undergo fragmentation , in which the worm breaks into several pieces, each of which develops into a new worm. Parthenogenesis also occurs in some species. With their soft bodies, earthworms do not fossilize well, though they may form trace fossils. Another species placed in the same genus was found in Herefordshire, England, but it is unclear whether these worms are in fact oligochaetes.

Stephenson postulated in that the common ancestor of oligochaetes came from the primitive aquatic family Lumbriculidae.

Because of its ability to colonise new areas and become dominant, the Lumbricidae has followed humans round the world and displaced many native species of earthworm. From Wikipedia, the free encyclopedia. This article is about the group of worms. For the plant genus, see Oligochaeta plant. Oxford University Press. Retrieved Ito, Nobuhiro Kaneko, Maurizio G. Paoletti, Sergei E. Van Praagh Megascolex Promegascolex mekongianus Cognetti, its extent, ecology and allocation to Amynthas Oligochaeta: Megascolecidae.

Opuscula Zoologica. Invertebrate Zoology, 7th edition. Cengage Learning. Invertebrate Zoology. Freshwater Animal Diversity Assessment. An Introduction to the Invertebrates. Cambridge University Press. Biology and Ecology of Earthworms. Categories : Composting Annelids Clitellata. Namespaces Article Talk. Views Read Edit View history. In other projects Wikimedia Commons Wikispecies.

By using this site, you agree to the Terms of Use and Privacy Policy. Earthworm Lumbricus terrestris.

Oligochaeta feeding level

Oligochaeta feeding level