TAILIEUCHUNG - SAT II Biology Episode 1 Part 9

Tham khảo tài liệu 'sat ii biology episode 1 part 9', ngoại ngữ, ngữ pháp tiếng anh phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | ORGANISMS AND POPULATIONS Jellyfish Hydra Cnidaria Cnidaria include the sea anemone hydra jellyfish and corals which secrete a hard coating around themselves for protection. There are two morphological forms the medusa and the polyp. The medusa is free-floating. In some cnidaria the two stages alternate throughout their life cycle with the polyp form producing the motile medusae which produce the sperm and egg. Cnidarians are radially symmetrical have a digestive cavity with only one opening and have a two-layered body wall. Planaria Platyhelminthes Platyhelminthes are planarians flukes and tapeworms. Planarians are free-living carnivores flukes are either internally or externally parasitic and live off the fluids of the host and tapeworms are internal parasites in the digestive tract of vertebrates. Tapeworms lack their own digestive system. Platyhelminthes are radially symmetrical the digestive cavity has only one opening and it is not a coelom or pseudocoelom. There is no circulatory system. The body wall is composed of three layers. Peterson s SAT II Success Biology E M t57j CHAPTER 6 Roundworm Nematodes Roundworms are the first organism with a complete digestive tract many are free-living and help recycle nutrients and several are parasitic such as the trichina worm. They are bilaterally symmetrical have a pseudocoelom and have three tissue layers in their body wall. They have a sac-body plan. They do have an organ level of organization. Rotifer Rotifer microscopic with several specialized organs. They are primarily filter feeders. Peterson s SAT II Success Biology E M tsS ORGANISMS AND POPULATIONS mouth Earthworm Annelid The segmented worms include the leeches a blood-sucking parasite the earthworms and the polychaete worms which occupy a mostly marine environment. At this point in the taxa the organisms are becoming more and more complex by either possessing an entire organ system or by one or more organ systems attaining

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