WebFeb 1, 2014 · Platyhelminthes (pla-te-hel-MIN-thes) is made of two Greek roots that mean "flat worms" [flat -plato (πλάτω); and worm -helmis (ελμισ)]. The reference is to the flattened nature of the animals in this phylum. The name was coined by Gegenbaur (1859). INTRODUCTION TO THE PLATYHELMINTHES. WebA fairly simple structure based on bilateral symmetry has flat worms. Its general characteristic is the following: the right and left halves of the body are mirror-like. Free-living flatworms have a flattened body shape and only one opening in the intestine is oral. The circulatory system these organisms are deprived.
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WebOne type of worm is the flatworm. Worms in the phylum Platyhelminthes are called flatworms because they have flattened bodies. There are more than 18,500 known species of flatworms. Features of Flatworms. The main characteristics of flatworms (Figure below) include: Flatworms have no true body cavity, but they do have bilateral symmetry. Platyhelminthes are bilaterally symmetrical animals: their left and right sides are mirror images of each other; this also implies they have distinct top and bottom surfaces and distinct head and tail ends. Like other bilaterians, they have three main cell layers (endoderm, mesoderm, and ectoderm), while the radially symmetrical cnidarians and ctenophores (comb jellies) have only two cell layers… scripps health obgyn
Introduction to the Platyhelminthes - University of …
WebSep 23, 2024 · Flatworms are acoelomate, triploblastic animals. They lack circulatory and respiratory systems, and have a rudimentary excretory system. ... The relationships among flatworms, or phylum Platyhelminthes, is being revised and the description here will follow the traditional groupings. Most flatworms are parasitic, including important … WebFlatworms range in length from about 1 millimeter (0.04 inches) to more than 20 meters (66 feet). They have a flat body because they do not have a coelom or even a pseudocoelom. They also lack a respiratory system. Instead, their cells exchange gases by diffusion directly with the environment. They have an incomplete digestive system. WebPlanarians are free-living flatworms. Like other flatworms the planarian has a bilateral body plan with a brain and stereo eyes that enable it to actively hunt. Unlike the flashy flatworms that live in the ocean, the thousands of species of planarians live either in freshwater or on land around the world. More Flatworms. scrippshealth org email