2-27-09 Lecture 17

2-27-09 Lecture 16 Still need to know terminology from first two weeks, but can forget everything else. Phylum Platyhelminthes (flat worms) Dorsoventrally flat Great deal of shapes and sizes (up to 60m) Acoelomates (fluid filled cavity) Lack colem Tripoblastic Bilaterally symmetric Tegument ? outer covering Syncitium ? single celled Evade host immune response Communicate with other parasites within the host Uptake of nutrients Monoecious ? hermaphroditic (functionally hermaphrodic ? when you have a single flat worm in one host but would rather be fertilized by another worm) Dioecious (few worm species have male and female individuals) Flame cell ? protonephridia - excretory system ? horse shoe with a flagella Ammonia or urea/uric acid Acoelomates Bilateria Class Turbellaria Planarians No economic or medical importance Free-living or terrestrial, marine and freshwater environments Primarially parasites to echinoderms Class Cestoidea Tape worms Parasitic to all vertebrates Class Monogenoidea All parasitic Parasites of cold blooded vertebrates ? usually fish Ectoparasites Live on scale or gills of fish Pistohaptor ? hold fast structure - sucker with hooks No economic or medical importance unless fish farms (like other factory farmed animals) these parasites can wipe out entire farms Monoxenous ? direct life cycle Adult ( eggs ( oncomiracidium (ciliated juvenile) ( Attach to DH ( Adult Monoecious Class Trematoda 2 Subclasses Aspibobothria ? not of any economic or medial importance but interesting life cucles ? link between free-living and parasitic parasites? Monoxenous (like monogenoidea) Midventral sucker with loculi or alveoli Lack anterior sucker Mostly free-living Some facultative/obligate parasites Parasites of mollusks on occasion Adult ( eggs ( cotylocidium (juvenile ? free-living or parasitic) ( adult Digenea (flukes) Important in terms of parasitic worms Cause significant economic loss through loss of domesticated animals 2 host life cycle (at least) DH and IH IH (gastropod mollusk ? snail) Parasite will alter host behavior to complete parasite life cycle Diamond/leaf shaped body form Body forms distinguishable by the placement of the acetabulum Know Shistosome because it has male and female body forms HAND OUT Acetabulum Midventral sucker ? holdfast mechanism Anterior sucker around mouth Distome ? most common body form Protandry ? since they are hermaphroditic, male reproductive system develops first Male reproductive structures: Testes Vas deferens Vasa efferentia Seminal vesicle ? sperm storage Prostate gland Ejaculatory duct Cirrus Cirrus pouch Genital pore Genital atrium Sometimes: Mo cirrus pouch No genital pre Female reproductive structures Ovary Oocapt ? oocytes - germ cells leave have not undergone meiosis yet Oviduct Seminal receptacle Vitelline related (cells, reservoir, duct, follicles) Mehlis gland Ootype Uterus