What is the scientific name for flatworms

"Platodes" from Ernst Haeckel"s Kunstforguys der Natur, 1909)Scientific classificationKingdom:AnimaliaPhylum:PlatyhelminthesGegenbaur, 1859Classes


The flatworms are a phylum, Platyhelminthes, of relatively basic, soft-bodied, bilaterially symmetrical, invertebrate animals. The name of the phylum comes from the Greek platy, interpretation "flat," and helminth, interpretation "worm," which is indicative of their ribbon-shaped, flattened appearance. They include the flukes and also tapeworms, among others.

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Flatworms are acoelomates that are defined by having 3 germ layers (ectoderm, mesoderm, and also endoderm) and also lacking respiratory and also circulatory devices. Acoelomates are invertebprices that carry out not have a coelom, or body cavity. With around 25,000 recognized species, flatworms are the largest phylum of acoelomates. Platyhelminths are thneed to be the first invertebprices to have a third germ layer, the mesoderm (Towle 1989).

Flatworms are found in marine, freshwater, and also damp terrestrial settings. They generally are put right into 4 classes: Trematoda (flukes), Cestoda (tapeworms), Monogenea, and Turbellaria. While many flatworms are complimentary living, many kind of are likewise parasitic. Turbellarians, such as planarias, tfinish to be free-living, while trematodes, cestodes, and also monogeneans live as parasites in, or on, various other animals. Several of these parasites are ingested by consuming undercooked food.

Depending on species and also age, individuals deserve to variety in size from practically microscopic to over 20 meters lengthy (some tapeworms deserve to acquire this length).



A flatworm"s soft body is ribbon-shaped, flattened dorso-ventrally (from height to bottom), and bilaterally symmetric. They are the easiest triploblastic animals through organs. This means their organ units create out of three germ layers: An outer ectoderm and also an inner endoderm, with a mesoderm between them.

Turbellarians mainly have actually a ciliated epidermis, while cestodes and also trematodes are covered via a cuticle (hard yet functional, non-mineral covering).

There is also no true body cavity (coelom) other than the gut, and also hence flatworms are acoelomates. The inner of the acoelomate body is filled via rather loosely spaced mesodermal tissue, dubbed parenchyma tworry.


Flatworms have actually no true circulatory or respiratory system, however favor all other animals, flatworms perform take in oxygen. Extracellular body fluids (interstitial fluids) percolate between cells to assist distribute nutrients, gases, and also waste products. Flatworms respire at their integument; gases diffuse directly throughout their moist outer surconfront. This form of system is dubbed integumentary exreadjust.

However before, flatworms perform have actually a bilateral nervous system; they are the easiest pets to have one. Two cord-favor nerves branch repeatedly in an array resembling a ladder. Flatworms have actually their feeling receptors and nerves concentrated on the anterior finish (cephalization). The head end of some species also has a collection of ganglia acting as a rudimentary brain to integrate signals from sensory organs, such as eyespots.

Usually the digestive tract has actually one opening, so the pet cannot feed, digest, and remove undigested pwrite-ups of food concurrently, as many pets via tubular guts have the right to. This gastrovascular cavity features similarly to that of the Cnidaria. However, in a few particularly lengthy flatworms, or those with extremely branched guts, tright here might be one or even more ansupplies. A little team wright here the gut is missing or non-permanent, referred to as acoel flatworms, appear to be unregarded the various other Platyhelminthes.

In spite of the simplicity of the digestive chamber, they are considerably more complicated than cnidarians in that they possess countless organs, and also are therefore shelp to present an body organ level of organization. The mesoderm permits for the development of these organs, and true muscle. Major feeling organs are concentrated in the front finish of the animals for species that possess these organs.

Muscular contractivity in the upper finish of the gut causes a solid sucking pressure, enabling flatworms to ingest their food and also tear it right into little bits. The gut is branched and exoften tends throughout the body, functioning in both digestion and also transport of food.


Flatworms exhilittle an undulating develop of locoactivity.

Flatworm reproduction is hermaphroditic, interpretation each individual produces eggs and also sperm. When two flatworms mate, they exchange sperm so both end up being fertilized. Some flatworms, such as Pseudobiceros hancockanus engage in penis fencing, in which two people fight, trying to pierce the skin of the various other through their penises. The initially to succeed inseminates the various other, which need to then bring and also nourish the eggs.<1> They normally perform not fertilize their very own eggs.

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Turbellarians classified as planarians (commonly freshwater, non-parasitic) have the right to likewise redevelop asexually by transverse fission. The body constricts at the midsection, and also the posterior end grips a substprice. After a few hrs of tugging, the body rips acomponent at the constriction. Each half grows replacements of the absent pieces to create 2 entirety flatworms.

This additionally suggests that if a flatworm is reduced in fifty percent, each fifty percent will regenerate right into two separate, fully-functioning flatworms.



The standard classifications of flatworms is primarily based upon differing degrees of parasitism and also separated right into three monophyletic classes:

The staying flatworms are grouped together for convenience as the course Turbellaria, currently making up the complying with orders:


Many of these orders of Turbellaria encompass free-living develops. The flukes and also tapeworms, though, are parasitic, and a few reason substantial damage to human beings and other pets.

Tapeworm infestations

Adult tapeworm infection is the infection of the digestive tract by parasitic cestodes, or tapeworms. Tapeworm larvae are sometimes ingested by consuming undercooked food. Once inside the digestive tract, the larva grows right into an adult tapeworm, which have the right to live for years and also flourish very large. In addition, many tapeworm larvae cause symptoms in an intermediate hold. For example, cysticercosis is a disease of humans involving larval tapeworms in the human body.

In a tapeworm infection, adult worms absorb food predigested by the hold, so the worms have actually no need for a digestive tract or a mouth. Large tapeworms are made practically entirely of reproductive structures via a small "head" for attachment. Symptoms vary commonly, depending on the species bring about the infection.

Among the a lot of prevalent tapeworms in human beings are the pork tapeworm, the beef tapeworm, the fish tapeworm, and the dwarf tapeworm. Infections including the pork and also beef tapeworms are likewise called taeniasis.

Taenia solium and Taenia saginata are common tapeworms. A person have the right to become infected by these parasites by eating rare meat that has been infected. Symptoms generally encompass abdominal pain, diarrhea, nausea, and other gastrointestinal ailments. Sometimes, the parawebsite may migrate to the appendix, pancreas, or bile duct, causing serious abdominal pain.

A dangerous complication of the parawebsite Taenia solium, Cysticercosis, may occur when the larvae build exterior the intestinal tract. This parasite deserve to relocate from the intestines to muscle tconcern, bone marrowhead, fingers, and in some instances, the main nervous device (neurocysticercosis). The last infection deserve to lead to seizures and also various other neurological troubles.

A 3rd form of tapeworm, Diphyllobothrium latum, is contracted by eating raw, infected fish. The fish come to be infected by eating infected crustaceans, which ended up being infected by consuming untreated sewage. This tapeworm outcomes in symptoms comparable to those of Taenia saginata and Taenia solium, but can additionally encompass weakness and also tiredness.<2>

Biochemical Memory

In 1955, Thompchild and also McConnell conditioned planarian flatworms by pairing a bbest light via an electric shock. After repeating this several times, they took ameans the electrical shock, and also only exposed them to the bideal light. The flatworms would react to the bbest light as if they had been shocked. Thompson and McConnell uncovered that if they cut the worm in 2, and also enabled both worms to regeneprice each fifty percent would construct the light-shock reactivity.

In 1962, McConnell repetitive the experiment, yet rather of cutting the trained flatworms in 2 he ground them right into small pieces and fed them to various other flatworms. Incredibility, these flatworms learned to associate the bideal light via a shock much much faster than flatworms who has actually not been fed trained worms.

This experiment showed that memory could perhaps be transferred chemically. The experiment was recurring with mice, fish, and rats, but it always failed to develop the exact same outcomes. Likewise, the findings with planarians could not be repeatedly replicated and also thus are rather controversial. An explacountry for this phenomenon in flatworms is still unrecognized this day.



Block, R. A, and also J. V. McConnell. 1967. Classically conditioned discrimicountry in the Planarian, Dugesia dorotocephala. Nature 215: 1465-1466.McConnell, J. V. 1962. Memory transfer with cannibalism in planarium. J. Neuropsychiat. 3 suppl 1: 542-548.Naganuma, K. H. 1997. Acoelomate Flatworms, Phylum Platyhelminthes. Lab handout presented in the Fevery one of 1997. (adapted GNU Free Documentation Licensed text: Permission granted in February 2005).Thompson, R. and also J. V. McConnell. 1955. Classical conditioning in planarian, Dugesia dorotocephala. J. Comp. Physiol. Psych. 48:65-68.


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