{"id":569,"date":"2020-09-21T09:27:47","date_gmt":"2020-09-21T09:27:47","guid":{"rendered":"https:\/\/www.guyhowto.com\/?p=569"},"modified":"2023-12-21T13:14:36","modified_gmt":"2023-12-21T13:14:36","slug":"phylum-platyhelminthes-the-flatworms","status":"publish","type":"post","link":"https:\/\/www.guyhowto.com\/phylum-platyhelminthes-the-flatworms\/","title":{"rendered":"Phylum Platyhelminthes -The Flatworms"},"content":{"rendered":"
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Phylum Platyhelminthes, commonly known as flatworms, represents a diverse group of invertebrate animals.<\/p>\n

These organisms are characterized by their flattened, ribbon-like bodies.<\/p>\n

Despite their simple appearance, flatworms exhibit a range of adaptations and complexities that make them interesting subjects for study.<\/p>\n

The word Platyhelminthes is derived from Greek which means “the flat”.<\/strong><\/p>\n

The name Platyhelminthes has been given to the group of flatworms and the body of these animals is soft and dorsoventrally compressed.<\/p>\n<\/div>\n

General Characteristics of Phylum Platyhelminthes<\/strong><\/h5>\n

Grade of organization:<\/strong> They are multicellular organisms and are triploblastic acoelomates i.e.<\/strong> they contain ectoderm and endoderm plus the development of mesoderm.<\/p>\n

Shape and Symmetry:<\/strong> The Phylum Platyhelminthes have bilateral symmetry and these organisms have an unsegmented body. The size ranges from a few millimeters (planaria) to several meter long animals(tapeworm).<\/p>\n

Habitat:<\/strong> Some members of Phylum Platyhelminthes are free-living, some live in freshwater and some are found in marine water.<\/p>\n

Special Body cells:<\/strong><\/p>\n

Flame cells:<\/strong> Flame cells are specialized excretory cells found in the flatworms. These are bulb-like cells. A flame cell has a tuft of cilia, whose beating propels interstitial fluid into the tubular system. The beating of cilia looks like a flickering flame; therefore, these cells are termed flame cells.<\/p>\n

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Sac-like digestive system<\/a>:<\/strong>\u00a0 The body space is mostly occupied by a branching sac type digestive system. The digestive system is poorly developed in some species or maybe absent as in the tape-worms.<\/p>\n

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Organs and Organ systems:<\/strong> They have sense organs at the anterior end but respiratory and circulatory systems are not present.<\/p>\n

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Nervous system<\/a>:<\/strong> There is a well developed nervous system but it may be in the form of a network f nerves or ganglia.<\/p>\n

Movement:<\/strong> The free-living kinds are motile. They shoe movement by cilia present in their undersides (Planaria). In parasitic types the motion is limited.<\/p>\n

Body in Phylum Platyhelminthes:<\/strong> The physique is dorsoventrally flattened and is unsegmented and looks like a leaf.<\/p>\n

Mode of nutrition: <\/strong>With few exceptions, the Platyhelminthes are all parasites, largely endoparasites, i.e., reside within their hosts. The most frequent cases include Taenia solium<\/em> (tapeworm), Fasciola hepatica<\/em> (liver fluke), and Schistosoma<\/em> (blood fluke). The parasites are more prevalent in tropics. A few of them cause diseases in people.<\/p>\n

Reproduction in Phylum Platyhelminthes<\/strong><\/h5>\n

In Platyhelminthes reproduction takes place by asexual as well as sexual means:<\/p>\n

Asexual reproduction:<\/strong><\/p>\n

Asexual reproduction is by fission where the organism constricts from the centre into two fragments, all fragments will regenerate the lost component.<\/p>\n

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Sexual reproduction:<\/strong><\/p>\n

The sexually reproducing species are hermaphrodite, i.e., both female and male reproductive organs exist in the same individual. Larval kind is occasionally present.<\/p>\n

Life cycle:<\/strong><\/p>\n

Parasitic platyhelminths undergo quite intricate life cycles, and often include many larval stages in different organisms — the intermediate hosts; these hosts might be invertebrate or vertebrate.<\/p>\n

Classification of Phylum Platyhelminthes<\/strong><\/h5>\n

Class Turbellaria<\/strong><\/p>\n

The Turbellaria includes chiefly free-living, marine species, though some species reside in freshwater or moist temperate environments. Hookers and suckers are not present.<\/p>\n

Examples: Planaria, Otoplana<\/p>\n

Class Cestoda<\/strong><\/p>\n

The cestodes, or tapeworms, are internal parasites, chiefly of vertebrates. Hooks and suckers are found for sucking digested substance from host species therefore digestive tract are also absent.<\/p>\n

Example: Taenia<\/p>\n

Class Trematoda<\/strong><\/p>\n

The trematodes, or flukes, are parasites of mollusks and a variety of different organisms, such as humans. They also have suckers as they are parasites and obtain food by sucking substances from the host.<\/p>\n

Example: Liver fluke<\/p>\n

Examples of Phylum Platyhelminthes<\/strong><\/h5>\n

Dugesia (Planaria):<\/strong> A free-living flatworm with cillias.<\/p>\n

\"Dugesia\"<\/p>\n

Fasciola (Liver luke):<\/strong> An endoparasite in sheep and sometimes in humans. It lives in the bile duct of its hosts.<\/p>\n

\"Fasciola\"<\/p>\n

Taenia (Tapeworm):<\/strong> An endoparasite of humans, cattle, and pig.<\/p>\n

\"Taenia\"<\/p>\n

FAQs about Phylum Platyhelminthes – The Flatworms<\/strong><\/h3>\n
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  1. What does the name “Platyhelminthes” mean?<\/strong>\n