Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Flatworms in the Food Chain The turbellarian flatworms living in
Document related concepts
no text concepts found
Transcript
FlatwormsintheFoodChain Theturbellarianflatwormslivinginfreshwaterarefree-livingandmostarecarnivores.Some speciesareefficientpredatorsthatfeedontinyinvertebratesandsmallcrustaceans.Others feedondetritusanddeadanimals.Flatwormsmayregulatepopulationdynamicsof zooplanktoninponds.Tinyturbellariansthatliveinspacesbetweensedimentfeedonparticles toosmallforotherorganismstoeat. Themarineflatworms(polycladids)arethelargestofthefree-livingflatworms.Some,likethe Persiancarpetflatworm,eatavarietyoffood.Theyfeedontunicates,smallcrustaceans, worms,andmolluscs.Theseflatwormsfeedlikeseastars,extrudingtheirpharynx,which secretesenzymestodigesttheirprey. Parasiticflatwormsplayaroleinkeepingthepopulationsofsomeanimalslow.Flukes (trematodes)areinternalparasitesofmolluscsandvertebrates,likefish.Flukesinclude18,000 to24,000speciesdividedintotwosubclasses.ThesmallerAspidogastrea,about100species, areobligateparasiteofmolluscsandmayalsoinfectturtlesandfish.Theothergroup,Digenea, comprisethemajorityoftrematodes;theyareobligateparasitesofmolluscsandvertebrates. Mosttrematodeshaveacomplexlifecyclewithatleasttwohosts.Theprimaryhost,wherethe flukessexuallyreproduce,isavertebrate.Theintermediatehost,inwhichasexual reproductionoccurs,isusuallyamollusc.
