what is the ecological importance of the planarians?
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Planaria sp. is a common freshwater, non-parasitic member of the phylum Platyhelminthes, class Turbellaria. It should be noted that the term "planaria" is most often used as a common name, much in the same way as trout. It is also the name of a genus within the family Planariidae. It moves by beating cilia on the ventral dermis, allowing it to glide along on a film of mucus. Some move by undulations of the whole body by the contractions of muscles built into the body wall. They exhibit an extraordinary ability to regenerate lost body parts. For example, a Planaria split length wise or crosswise will regenerate into 2 separate individuals. The size ranges from 3 to 12 mm, and the body has two eye-spots (also known as ocelli) that can detect the intensity of light. The eye-spots act as photoreceptors and are used to move away from light sources. Planaria have 3 germ layers (ectoderm, mesoderm, and endoderm), but lack a body cavity or coelom. They have a single-opening digestive tract, consisting of one anterior branch and two posterior branches in freshwater planarians. Because of this three-branched organization, freshwater flatworms are often referred to as triclad planarians.\n\nPlanaria are common to many parts of the world and reside in fresh water ponds and rivers. They are also commonly found residing on plants.\n\nThe most frequently used in the high school and first-year college laboratories is the brownish Dugesia tigrina. Other common varieties are the blackish Planaria maculata and Planaria dorotocephala. Recently, however, the species Schmidtea mediterranea has emerged as the species of choice for modern molecular biological and genomic research due to its diploid chromosomes and existence in both asexual and sexual strains. Recent genetic screens utilizing double-stranded RNA technology have uncovered 240 genes that affect regeneration in S. mediterranea. Interestingly, many of these genes are found in the human genome (see link below).\nContents\n[show]\n\n    * 1 Organ Systems\n    * 2 See also\n    * 3 External links\n    * 4 References\n\n[edit]\n\nOrgan Systems\n\nThe planarian has very simple organ systems. The digestive system consists of a mouth, pharynx, and an intestine. The mouth is located in the center of the underside of the body. Digestive enzymes sercrete from mouth to begin external digestion. The pharynx connects the mouth to the intestines. The intestines of the Planaria branch throughout the body. They eat living or dead small animals which they suck with their muscular mouth. From there the food passes through the pharynx into the intestines and digesting of the food takes place in the cells lining the intestine, which then diffuses to the rest of the body. The undigested food leaves through the pharynx and mouth.\n\nPlanaria receive oxygen and release carbon dioxide by diffusion. The excretory system is made of many tubes with many flame cells and excretory pores on them. Flame cells remove unwanted liquids from the body by passing them through ducts that lead to excretory pores where the waste is released on the dorsal surface of the planarian.\n\nAt the head of the planarian there is a brain under the eyespots. From the brain there are two nerve cords which connect at the tail. There are many transverse nerves connected to the nerve cords which make it look like a ladder. With a ladder-like nerve system it is able to respond in a coordinated manner.\n\nA planarian can reproduce either asexually or sexually. In asexual reproduction the planarian detaches its tail end and each half regrows the lost parts. In sexual reproduction each Planaria gives and receives sperm. Planaria have both testes and ovaries. Eggs develop inside the body and are shed in capsules. Weeks later the eggs hatch and grow into adults. Planarians can also reproduce by regeneration. If a Planaria is cut into two halves both halves may become two new Planaria (regeneration). In one experiment, T.H. Morgan found th
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plankton and zooplankton
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See the link and scroll down to "earthworm" for an interesting discussion of its segments and what they do.  One segment has the brain which controls movement.  Good luck.
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Its very important as it breathe and produce loads of oxygen. Even though its under water it balance total environment. \n\nI hope the first answer didn't serve you..!
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Oh well, with that information it's easy to identy. \n\nThe  creature is Biplaium kewense. They are commonly known as "worm killers".  See the link below for some photos\n\nAs others have guessed it is a planarian. Worm killers are an exotic pest species imported from Viet Nam in the soil of potted plants. They are carnivorous and hunt earthworms and small insects. They immobilise their prey by coating them with that slime they secrete and then stick a tube into them and suck their insides out.\n\nBTW, well spotted that it uses it's head like a sensor. That is exactly what they do. There are pits under the head that act like a nose that enables the animal to track earthworms, slugs and other prey animals.
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You could have looked this up... here are some sites, but I recommend the book Invertebrates by Brusca & Brusca; it has excellent and clear illustrations.\n\nhttp://bugs.bio.usyd.edu.au/Entomology/ExternalMorphology/imagePages/mouth_butterfly.html\nhttp://www.enchantedlearning.com/bgifs/Bflyhead.GIF
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Ok, you probably mean the zooplankton.\nGenerally, you would name producers the algae (phytoplankton), that   photosynthesise, primary consumers the zooplankton (or some small fish, or some insects, crustaceans, etc) that eat the producers (they are herbivorous) and secondary producers the fish or crustaceans etc that eat the primary consumers.\nIn a pond ecosystem, the main primary consumers would be some insects and zooplankton, and secondary consumers some bigger animals (not necessarily aquatic)\nI would give you some on-line references but I do not know what exactly you need to find, or how specific or general information you need. Anyways, I give you a couple of websites, but I really don't know what exactly you need.\nIf you posted a comment with more details, I could edit my answer, trying to include more info
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94. Annelida\n95. Echinodermata\n96. Mollusca\n97. Arthropoda
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Sponge larvae aren't sessile.\n\nThey catch their prey and eat them, and they don't photosynthesize.
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Species are dying out all the time. And this effects the ecological balance. Therefore conservation biology can help to maintain species and prolong others lives. This is a must in research otherwise there will be nothing to research.
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Soil invertebrates play important roles in soil communities. Some directly consume detritus, others consume detritivores, whereas others are higher-level carnivores that can indirectly control decomposition by their effects on lower levels of the food web. The classic study of detrital food webs was conducted by Gist and Crossley (1975), showing which invertebrate groups are detritivores and which are carnivorous. This reference is somewhat hard to find; Smith and Smith (2001, p. 496) has a good description of the major findings of that study.\n\n\nVisit the link below for all the info.
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First education.  Especially where animal habitat is involved.  The first site below list several good resources.\nSecond, group action.  This is very important in both the developed countries as well as third world nations.\nFinally, human population reduction or at least stability.  This is the most important in countries like the United States where one child can use more resources than a whole village in another part of the world.
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Such a thing does occur among small animals such as planaria. The exchange of gases and therefore the exertion and movement such animals can perform is very limited. Microbes do not have a real respiratory system nor a circulatory systems in the terms we consider customary. It does limit the range and degree of motion. Gas exchange and work is severely limited. I see no advantages unless one wishes to become a planarian.
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If by "red worms" you mean earthworms of the species Eisenia foetida (commonly used for composting), they mostly eat any plant or animal particulate matter that is small enough to enter their mouths; other species (including another common earthworm of genus Lumbricus) can use their sucker-like mouth to ingest relatively large pieces of food. They also ingest live microorganisms along with the detritus. \nEarthworms are part of the soil mesofauna, and usually they don't feed on whole plant parts (such as leaves) but rather on small pieces of particulate matter that have already been generated by other animals of the macro- and mesofauna, especially plant residues (coffee grounds and tea leaves included). They ingest these along with soil inorganic particles (that's why they are important for mixing and carrying organic matter into deeper soil layers).
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They have a key role to play in marine ecosystems and erosion of shores.
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They've got the starring role! Bacteria, fungi, protists, all of them pick away at whatever dead matter they find, and the important thing is that they often secrete digestive enzymes onto the stuff so it breaks down. This helps them have small food particles to ingest, and it cleans up the environment to boot.
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Although often inconspicuous, fungi occur in every environment on Earth and play very important roles in most ecosystems. Along with bacteria, fungi are the major decomposers in most terrestrial (and some aquatic) ecosystems, and therefore play a critical role in biogeochemical cycles and in many food webs.\n\nMany fungi are important as partners in symbiotic relationships with other organisms, as mutualists, parasites, or commensalists, as well as in symbiotic relationships that do not fall neatly into any of these categories. One of the most critically important of these relationships are various types of mycorrhiza, which is a kind of mutualistic relationship between fungi and plants, in which the plant's roots are closely associated with fungal hyphae and other structures. The plant donates to the fungus sugars and other carbohydrates that it manufactures from photosynthesis, while the fungus donates water and mineral nutrients that the hyphal network is able to find much more efficiently than the plant roots alone can, particularly phosphorus. The fungi also protect against diseases and pathogens and provide other benefits to the plant. Recently, plants have been found to use mycorrhizas to deliver carbohydrates and other nutrients to other plants in the same community and in some cases can make plant species that would normally exclude each other able to coexist in the same plant community. Such mycorrhizal communities are called "common mycorrhizal networks". Over 90% of the plant species on Earth are dependent on mycorrhizae of one type or another in order to survive, and it is hypothesized that the presence of terrestrial fungi may have been necessary in order for the first plants to colonize land.\n\n\n\nIn soil, microorganisms which reside in the rhizosphere (a zone that includes the root surface and the soil that adheres to the root after gentle shaking) help in the transformation of molecular dinitrogen gas as their source of nitrogen, converting it to nitrogenous compounds in a process known as nitrogen fixation. This serves to provide an easily absorbable form of nitrogen for many plants, which cannot fix nitrogen themselves. Many other bacteria are found as symbionts in humans and other organisms. For example, the presence of the gut flora in the large intestine can help prevent the growth of potentially harmful microbes.\n\nThe ability of bacteria to degrade a variety of organic compounds is remarkable. Highly specialized groups of microorganisms play important roles in the mineralization of specific classes of organic compounds. For example, the decomposition of cellulose, which is one of the most abundant constituents of plant tissues, is mainly brought about by aerobic bacteria that belong to the genus Cytophaga. This ability has also been utilized by humans in industry, waste processing, and bioremediation. Bacteria capable of digesting the hydrocarbons in petroleum are often used to clean up oil spills. Some beaches in Prince William Sound were fertilized in an attempt to facilitate the growth of such bacteria after the infamous 1989 Exxon Valdez oil spill. These efforts were effective on beaches that were not too thickly covered in oil.\n\nBacteria, often in combination with yeasts and molds, are used in the preparation of fermented foods such as cheese, pickles, soy sauce, sauerkraut, vinegar, wine, and yogurt. Using biotechnology techniques, bacteria can be bioengineered for the production of therapeutic drugs, such as insulin, or for the bioremediation of toxic wastes.\n\n"Friendly bacteria" is a term used to refer to those bacteria that offer some benefit to human hosts, such as Lactobacillus species, which convert milk protein to lactic acid in the gut. The presence of such bacterial colonies also inhibits the growth of potentially pathogenic bacteria (usually through competitive exclusion). Other bacteria that are helpful inside the body are many strains of E. coli, which ar