WFSC 335 Exam # 2 Study Guide

Phylum Platyhelminthes

 Acoelomate  Bilaterally symmetrical and sometimes display cephalizationwhere sensory organs tend to be towards the anterior end of the organism  Triploblastic  Dorso-ventrally flattened  3 well developed muscle layers o Circular o Longitudinal o Oblique (transverse) Digestive System:  Mouth, pharynx, gastrovasuclar cavity o No anus b/c mouth is used for ingestion and egestion Nervous System:  Ganglia (basic brain), transverse nerves, nerve cord, eyespot Excretory system:  Protonephiridia  flame cells, ducts, and pores  Excretory pore  Excretory canals Reproduction:  Hermaphrodites but do NOT self fertilize, reproduce sexually  Testissperm duct  Ovariesoviduct  Yolk gland 4 classes: 3 parasitic and 1 free living  Turbellia (free living) o Mostly aquatic o Body covered with cilia o Rhabdites – secretions released by glands to form mucus; aid in movement o Most have eye spots except those species that live in caves o Auricle – ear like projections o Hermaphroditic but also reproduce asexually by fission or budding o Vitellaria – female reproductive system o Planaria: . Dugesia species . Largest of freshwater triclads (4-30 mm in length)  Triclad – intestine has 3 branches, which is where the name triclad comes from . Freshwater carnivores . Move by using cilia  Monogenea o Have Syncytial epidermis – multinucleated cell mass from fusion of cells (one huge skin cell) o Marine and freshwater o Mostly ectoparasites of aquatic . 1 during lifecycle, no intermediate host o Has suckers and clamps o Opisthaptor – posterior hook attachment o Hermaphroditic (monoecious) . Reproduce sexually inside host o Direct development . Free swimming larvae (gyrodactyloid)  (“Flukes”) o Have Syncytial epidermis – multinucleated cell mass from fusion of cells (one huge skin cell) o Parasitic most have intermediate host (usually invertebrates) . Endo and ectoparasites . Reproduce asexually and sexually  Only reproduce sexually once in adult stage  Reproduce asexually in intermediate host o 2 subclasses . Aspidogastrea  Large ventral sucker divided by septa, forming row or suckers  Alveoli – suckerlets  Simple life cycle . Digeneans (2 generations)  endoparasites (intestines)  life cycle: alternation of generation-like system composed of an asexual aspect (Polyembryony) invertebrate intermediate host and sexual phase (Anisogamy) vertebrate definitive host  incomplete digestive tract with no anus  (Tapeworms): o Have Syncytial epidermis – multinucleated cell mass from fusion of cells (one huge skin cell) o Primarily found in intestines of vertebrates as adults and in the coelom of the definitive host o Adults usually have 2 or more suckers or sucking surfaces on specialized attachment called scolex (anchor) o No digestive organs o Monoecious o Indirect development with 2 hosts o Body is made up of 4 segments . Scolex (head) . Immature proglottid . Mature proglottid . Gravid proglottid o 1 set of male and female reproductive organs in each proglottid o Subclass Cestodaria . Primitive tapeworms . Mostly body cavity parasites (not intestinal tract) . Neotenic – larva may be able to reproduce without adult stages . Unsegmented body, no scolex . Hermaphroditic no need for sexual reproduction and only 1 set of male and female organs per individual unlike “true” tapeworms o Subclass (True Tapeworms) . Order Pseudophyllidea  Bothraited scolex – shallow sucking grooves  Vitellaria and testes scattered laterally  Genital pore located medially  Eggs operculated and protein tanned  Life cycles generally use 3 hosts2 intermediate hosts and the definitive host . Order Proteocephalata  Parasites as adults in freshwater fish, amphibians, and  Have acetabulate scolex – cup like with a muscular wall  Testes and vitellaria scattered laterally in proglottids  Genital pore is laterally situated  Uterus is saccate . Order  Parasites as adults in and  Life cycles are terrestrial NOT aquatic o Generally involve intermediate host o Larvae are some form of a bladder worm  Acetabulated scolex/rostellum present  Genital pores are laterally situated  Vitellaria compact in posterior region of proglottid