Platyhelaninthes

1. Platyhelaninthes By Austin N, Jacob L, Belle Paucar

2. General description • The flatworms, flat worms, Platyhelminthes, Plathelminthes, or platyhelminths are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates. Unlike other bilaterians, they are acoelomates, and have no specialized circulatory and respiratory organs, which restricts them to having flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion. The digestive cavity has only one opening for both ingestion and egestion; as a result, the food cannot be processed continuously.

3. Symmetry • Are a phylum of triploblastic acoelomate invertebrate animals. The word Platyhelminthes comes from the Greek words 'platy' meaning flat and 'helmins' meaning worm. Their worm like bodies are soft, unsegmented, dorsoventrally flattened with bilateral symmetry, and resemble ribbons.

4. Feeding • Platyhelminthes are filter feeders • Cnidarians • They are carnivore • They are herbivore • Platyhelminthes is an extremely bad parasite in the South-Eastern

5. Circulation  • Platyhelminthes does not have a circulatory system. • Its replaced by diffusion. • Diffusion: Net movement of molecules or atoms from a region high concentration.

6. Excretion • The digestive cavity has only one opening for both intake of food and the excretion of it; as a result, the food cannot be processed continuously. Their excretory system consists of protonephridia.

7. Response • Most flatworms have more complex structures for detecting and responding to external stimuli than those of cnidarians or sponges. They have ganglia, which controls their nervous system. Parasitic flatworms interact little with their external environment and typically have a less complex nervous system. They have eyespots that can detect changes in the amount of light in their environment. In addition to that, most have specialized cells that detect external stimuli, such as chemicals found in food or the direction in which water is flowing.

8. Movement • Free-living flatworms typically move in two ways, such as cilia  and muscles cells.

9. Reproduction • Most of them are hermaphrodites that reproduce sexually, but asexual reproduction is common also. Parasitic flatworms often have complex life cycles that involve both sexual and asexual reproduction.

10. Respiration • Respiration occurs throughout the surface of the body, thereby making the Platyhelminthes susceptible to loss of precious body fluids. This can result into dehydration. Thus these animals are restricted to living in a wet environment, such as in freshwater, sea or in moist terrestrial environment.

11. Trematoda                                             Planaria Cestoda • Fasciola Hepatica                                                                                                        Taenia Solium • Schistoma                                                                      Taenia Saginata

12. Vocabulary  • Pharynx: the membrane-lined cavity behind the nose and mouth, connecting them to the esophagus. • Flame cell: A flame cell is a specialized excretory cell found in the simplest freshwater invertebrates • Proglottid: each segment in the strobila of a tapeworm, containing a complete sexually mature reproductive system. • Scolex: the anterior end of a tapeworm, bearing suckers and hooks for attachment. • Hermaphrodite: a person or animal having both male and female sex organs or other sexual characteristics, • Central nervous system:the complex of nerve tissues that controls the activities of the body. In vertebrates it comprises the brain and spinal cord.

13. Works Cited • https://hubpages.com/education/Classes-of-platyhelminthes • https://en.wikipedia.org/wiki/Flatworm • https://biologywise.com/characteristics-of-platyhelminthes • https://zoology2014underdahl.weebly.com/platyhelminthes.html