The body of annelids is divided into sections by septa (membranes). Each section is a compartment. Its movement is a result of the action of body-wall muscles on incompressible fluids in the compartments (segments). Therefore, a compartment that contracts in diameter must simultaneously increase in length. There are three classes in this phylum.
Class Oligochaeta includes the earthworm; they are usually found in fresh water or moist soil, lack a well-developed head, and have few setae per segment. Earthworm activity aerates and mixes the soil, and is constructive to mineralization and nutrient 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 beneficial to the organic gardener.
In fact as long ago as 1881 Charles Darwin wrote: “It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organized creatures “ (The Formation Of Vegetable Mould Through The Action Of Worms, Charles Darwin) Anatomy Of Earthworm The basic body plan of an earthworm is a tube, the digestive system, within a tube, the muscular slimy, moist outer body. The body is annular, formed of segments that are most specialized in the anterior. Earthworms have a simple circulatory system.
They have two main blood vessels that extend through the length of their body: a ventral blood vessel which leads the blood to the posterior end, and a dorsal blood vessel which leads to the anterior end. The dorsal vessel is contractile and pumps blood forward, where it is pumped into the ventral vessel by a series of “hearts” (aortic arches) which vary in number in the different taxa. A typical lumbricid will have 5 hearts. The blood is distributed from the ventral vessel into capillaries on the body wall and other organs and into a ascular sinus in the gut wall, where gases and nutrients are exchanged. This arrangement may be complicated in the various groups by suboesophageal, supraoesophageal, parietal and neural vessels, but the basic arrangement holds in all earthworms. These single celled earthworms eat in a unique way: their mouth cavity connects directly into the digestive tract without any intermediate processes. Most earthworms are decomposers feeding on undecayed leaf and other plant matter, others are more geophagous.
Earthworms are also called megadriles (or big worms), as opposed to the microdriles (or small worms) in the families Tubificidae, Lumbriculidae, and Enchytraeidae, among others. The megadriles are characterized by having a multilayered clitellum (which is much more obvious than the single-layered one of the microdriles), a vascular system with true capillaries, and male pores behind the female pores. External Anatomy Of The Earthworm Internal Anatomy Of The Earthworm Picture and Article Method I do my research by surfing the Internet. Below are the websites that I surfed to complete my research on ‘The Locomotion In An Earthworm’ :- > <> <> <> <> Credit Firstly, I would like to thank my Biology teacher, Puan ________ for her support and guide. She help us a lot for this ‘Folio Biology’. Besides, I would like to thank my friends who helped and gave me their suggestions and ideas to complete this folio. CONTENTS Content Page 1. Credit 2. Objectives 3. Method 4. Introduction 5. Researches 6. Conclusion 7. Picture and Article Objectives From this folio, I able to :- Conclusion The earthworm’s existence cannot be taken for granted. Dr. W. E.
Shewell Cooper observed “tremendous numerical differences between adjacent gardens” (Soil, Humus And Health), and worm populations are affected by a host of environmental factors, many of which can be influenced by good management practices on the part of the gardener or farmer. Darwin estimated that arable land contains up to 53,000 worms per acre (13/m? ), but more recent research from Rothamsted Experimental Station has produced figures suggesting that even poor soil may support 250,000/acre (62/m? ), whilst rich fertile farmland may have up to 1,750,000/acre (432/m? , meaning that the weight of earthworms beneath the farmer’s soil could be greater than that of his livestock upon its surface. One thing is certain however: rich, fertile soil that is cared for organically and well-fed and husbanded by its steward will reap its reward in a healthy worm population, whilst denuded, overworked, and eroded land will almost certainly contain fewer, scrawny, undernourished specimens. Locomotion In An Earthworm Earthworms are basically a series of small segments or balloons connected end to end and separated by a septum that prevents a compressed fluid from .
Each segment has a set of antagonistic muscles. The inner muscles are circular which when they contract force the body or coelomic fluids (mostly water) to move toward each end of the segment, or both anterior and posterior. The outer muscles are longitudinal muscles that follow the long axis of the body. The longitudinal muscle fibers extend through two or three segments. When the longitudinal muscles contract, the fluid moves 360 degrees around the diameter of the worm resulting in segments that are short and wide.
Locomotion of an earthworm begins with the contraction of circular muscles at the anterior end of the worm. This contraction moves as a peristaltic wave to the posterior end of the worm. Each wave of circular muscle contraction is followed by a wave of longitudinal muscle contraction. Then another wave of circular muscle contraction begins, and so ad infinitum. The whole burrowing process is aided by the secretion of lubricating mucus. Worms can make gurgling noises underground when disturbed as a result of the worm moving through its lubricated tunnels.
They also work as biological “pistons’ forcing air through the tunnels as they move. Regeneration Of Earthworm Earthworms have the facility to regenerate lost segments, but this ability varies between species and depends on the extent of the damage. Stephenson (1930) devoted a chapter of his monograph to this topic, while G. E. Gates spent 20 years studying regeneration in a variety of species, but “because little interest was shown”, Gates (1972) only published a few of his findings that, nevertheless, show it is theoretically possible to grow two whole worms from a bisected specimen in certain species.
Gates’s reports included: Reproduction Of Earthworm Earthworm Reproduction Earthworms are hermaphrodites: They typically have 2 pairs of testes, surrounded by 2 pairs of testes sacs. There are 2 or 4 pairs of seminal vesicles which produce, store and release the sperm via the male pores, and ovaries and ovipores in segment 13 that release eggs via female pores on segment 14. However, most also have one or more pairs of spermathecae (depending on the species) that are internal sacs which receive and store sperm from the other worm in copulation.
Some species use external spermatophores for transfer instead. Earthworm Cocoons 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. The cocoon, or egg case, is secreted by the clitellum band which is near the front of the worm, but behind the spermathecae. Some time after copulation, long after the worms have separated, the clitellum secretes the cocoon which forms a ring around the worm.
The worm then backs out of the ring, and as it does so, injects its own eggs and the other worm’s sperm into it. As the worm slips out, the ends of the cocoon seal to form a vaguely lemon-shaped incubator (cocoon) in which the embryonic worms develop. They emerge as small, but fully formed earthworms, except for a lack of the sex structures, which develop later in about 60 to 90 days. They attain full size in about one year. Several common earthworm species are mostly parthenogenetic, that is, with asexual reproduction resulting in clones. Earthworm Special Habitats
The main habitat of earthworms is in soil, the situation is more complicated than that. The brandling worm Eisenia fetida lives in decaying plant matter and manure. Arctiostrotus vancouverensis from Vancouver Island and the Olympic Peninsula is generally found in decaying conifer logs or in extremely acidic humus. Aporrectodea limicola and Sparganophilus and several others are found in mud in streams. Some species are arboreal. Even in the soil species, there are special habitats, such as soils derived from serpentine which have an earthworm fauna of their own.
Importances Of Earthworm To Soil Biological In many soils, earthworms play a major role in converting large pieces of organic matter (e. g. dead leaves) into rich humus, and thus improving soil fertility. This is achieved by the worm’s actions of pulling down below any organic matter deposited on the dried dirt, such as leaf fall or manure, either for food or when it needs to plug its burrow. Once in the burrow, the worm will shred the leaf and partially digest it, then mingle it with the earth by saturating it with intestinal secretions.
Worm casts (see below) can contain 40% more humus than the top 9” of soil in which the worm is living. Faeces in form of casts. Chemical As well as dead organic matter, the earthworm also ingests any other soil particles that are small enough—including stones up to 1/20 of an inch (1. 25mm) across—into its gizzard wherein minute fragments of grit grind everything into a fine paste which is then digested in the stomach. When the worm excretes this in the form of casts which are deposited on the surface or deeper in the soil, minerals and plant nutrients are made available in an accessible form.
Investigations in the US show that fresh earthworm casts are 5 times richer in available nitrogen, 7 times richer in available phosphates and 11 times richer in available potash than the surrounding upper 6 inches (150 mm) of soil. In conditions where there is plenty of available humus, the weight of casts produced may be greater than 4. 5 kg (10 lb) per worm per year, in itself an indicator of why it pays the gardener or farmer to keep worm populations high. Physical
By its burrowing actions, the earthworm is of great value in keeping the soil structure open, creating a multitude of channels which allow the processes of both aeration and drainage to occur. Permaculture co-founder Bill Mollison points out that by sliding in their tunnels, earthworms “act as an innumerable army of pistons pumping air in and out of the soils on a 24 hour cycle (more rapidly at night). Thus the earthworm not only creates passages for air and water to traverse, but is itself a vital component in the living biosystem that is healthy soil.
Earthworms continue to move through the soil due to the excretion of mucus into the soil that acts as a lubricant for easier movement of the worm. Ecology Of Earthworm Earthworms are classified into three main ecophysiological categories: (1) leaf litter/compost dwelling worms (epigeic) e. g. Eisenia fetida; (2) topsoil or subsoil dwelling worms (endogeics); and (3) worms that construct permanent deep burrows through which they visit the surface to obtain plant material for food, such as leaves (anecic), e. g. Lumbricus terrestris.
Earthworm populations depend on both physical and chemical properties of the soil, such as soil temperature, moisture, pH, salts, aeration and texture, as well as available food, and the ability of the species to reproduce and disperse. One of the most important environmental factors is pH, but earthworms vary in their preferences. Most earthworms favor neutral to slightly acidic soil. However, Lumbricus terrestris are still present in a pH of 5. 4 and Dendrobaena octaedra at a pH of 4. 3 and some Megascolecidae are present in extremely acid humic soils.
Soil pH may also influence the numbers of worms that go into diapause. The more acid the soil, the sooner worms go into diapause, and remain in diapause the longest time at a pH of 6. 4. Earthworms form the base of many food chains. They are preyed upon by many species of birds, e. g. starlings, thrushes, gulls, crows, and both European Robins and American Robins. Some snakes feed on them and mammals such as bears, foxes, hedgehogs and moles eat many earthworms as well. Earthworms are also eaten by many invertebrates such as ground beetles and other beetles, snails, slugs.
Earthworms have many internal parasites including Protozoa, Platyhelminthes, Nematodes. They are found in many parts of earthworms’ bodies such as blood, seminal vesicles, coelom, intestine, or in the cocoons. The application of chemical fertilizers, sprays and dusts can have a disastrous effect on earthworm populations. Nitrogenous fertilizers tend to create acid conditions, which are fatal to the worms, and often dead specimens are to be found on the surface following the application of substances like DDT, lime sulphur and lead arsenate.
In Australia, the use of superphosphate on pastures almost completely wiped out the giant Gippsland earthworm. Therefore, the most reliable way to maintain or increase the levels of worm population in the soil is to avoid the application of artificial chemicals. Adding organic matter, preferably as a surface mulch, on a regular basis will provide them with their food and nutrient requirements, and also creates the optimum conditions of heat (cooler in summer and warmer in winter) and moisture to stimulate their activity.
A recent threat to earthworm populations in the UK is the New Zealand Flatworm (Artiposthia triangulata), which feeds upon the earthworm, but in the UK has no natural predator itself. At present sightings of the New Zealand flatworm have been mainly localised, but this is no reason for complacency as it has spread extensively since its introduction in 1960 through contaminated soil and plant pots. Any sightings of the flatworm should be reported to the Scottish Crop Research Institute, which is monitoring its spread. Folio Biology Chapter 2. 1 : “Locomotion In An Earthworm” Written by Administrator | |Monday, 03 September 2007 | |Keeping Your Soil Healthy | |By Jean Fritz | |August 26, 2007 | |Chicken Soup for the Soil | |Your soil is the most important part of your garden, but too many people forget to nurture their soil. Soil is a living thing, | |containing microbes, fungi, insect life and general “creepy-crawlies” vital to plant health and vigor, as well as a receptacle | |for chemicals and trace elements. Doing a little soil prep every fall pays off each and every harvest. | |First, add more organic matter. Use your rototiller or your spade, and dig under frostbitten plant material, grass clippings, | |leaves, wood chips, and compost.
Avoid using any diseased plant material as compost burn it first if there are no local | |restrictions on burning. If you live near any livestock, cover your garden with 1 2 of uncomposted manure, then disguise that | |with other organic materials, and let the whole thing winter over. A blanket of snow from December through March will turn all | |of it into about of the most beautiful topsoil you can imagine. | |Its also time to think about soil pH, or the acidity or alkalinity. The addition of organic materials can lower the pH, or make | |it more acidic. If your soil is already high in acid and you would like to neutralize it, you can also add lime or wood ashes to| |your garden.
Wood ashes are wickedly alkaline, but after a season or two, create an excellent haven for earthworms and add | |enough potash to the soil to grow wonderful root crops. | |Finally, feed your fungi. Really. Many stores specializing in products for organic gardening and sustainable agriculture sell | |micorrhizal spores, which is a fungus that helps soil release its nutrients more easily. Micorrhiza needs to be fed in order to | |reproduce and survive the winter. Use a hose-end sprayer, and fill it halfway with gooey, blackstrap molasses. If you can find | |the sulphured kind, so much the better. Fill the rest of the sprayer with flat beer, and spray the solution over your garden | |beds.
The sugar in the molasses feeds the existing fungi and beneficial bacteria in the soil, and the yeasts and enzymes in the | |beer add more. You’ll literally make your soil come alive, and that will help your garden thrive next year. | |Jean Fritz is a farmer and freelance writer. She owns and operates KittyVista Organics, a small organic farm located east of | |Indianapolis which specializes in heirloom, open pollenated and unusual varieties of flowers and vegetables | | | |Source : http://www. wormdigest. org |