The Skeletal System of Platyhelminthes
Platyhelminthes are characterized as being either soft-bodied or lacking cuticles and don't have the rigid skeletal support system found in a more complex phylum. Most Platyhelminthes come in flat ribbion or leaf like shapes. They are usually unsegmented and invertebrate animals.
Dugesia tigrina
(Freshwater Planarian) The Planarian's skeletal support comes in the form of connective tissue known as the parenchyma, which is located between the body wall and the gut. Despite this connective tissue, like all Platyhelminthes, the Planarian lacks an actual skeleton. Instead the Planarian makes use of its cilia for locomotive purposes and has two layers of muscles to help it move around.
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Diphyllobothrium latum
(Broad Fish Tapeworm) The Broad Fish Tapeworm, itself is composed of three segments the scolex (head), the neck, and the lower body. The head of the worm has a groove like slit on each side and from the neck there are growths of numerous proglottid segments which contain the reproductive organs of the worm.
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Clonorchis sinensis
(Chinese Liver Fluke) The Chinese Liver Fluke is soft bodied. It lives in the host's liver and feeds on bile. This makes the liver fluke use a hydro-static system to have the shape it has. This means that for support and to give resistance to the muscles they have fluid filled spaces forming a hydro-static skeleton.
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