![]() ![]() These are free-living organisms found mostly in freshwater. This was artificial but in 1985, Ehlers proposed a phylogenetically more correct classification, where the massively polyphyletic "Turbellaria" was split into a dozen orders, and Trematoda, Monogenea, and Cestoda were joined in the new order Neodermata. ![]() There are four groups that are Turbellaria, Trematoda, Monogenea, and Cestoda. ![]() Presence of parenchyma in the body cavity. Some of the characteristics that distinguish the organisms belonging to phylum Platyhelminthes from others are: Unique Characteristics of Platyhelminthes The nervous system comprises the brain and two longitudinal nerve cords arranged in a ladder-like fashion. The flame cells help in excretion and osmoregulation. They possess the quality of regeneration. The life cycle is complicated with one or more larval stages. They reproduce sexually by fusion of gametes and asexually by regeneration by fission and regeneration. They are hermaphrodites, i.e., both male and female organs are present in the same body. The space between the body wall and organs is filled with connective tissue parenchyma which helps in transporting the food material. They have an organ system level of organization. They respire by simple diffusion through the body surface. They are devoid of the anus and circulatory system but have a mouth. Their body is dorsoventrally flattened without any segments and appears like a leaf. The body has a soft covering with or without cilia. They are triploblastic, acoelomate, and bilaterally symmetrical. ![]() Platyhelminthes have the following important characteristics: Platyhelminthes are triploblastic, bilaterally symmetrical, dorsoventra, acoelomate flatworms with organ grade of construction without a definite anus, circulatory, skeletal or respiratory system but with Protonephridial excretory system and mesenchyme filling the space between the various organs of the body. Members of this phylum range in size from a single-celled organism to around 2-3 feet long. These are acoelomates and they include many free-living and parasitic life forms. The organisms are also known as flatworms. Phylum Platyhelminthes belongs to the kingdom Animalia. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |