BI256 Flatworms and Friends Lab Quiz PDF

BI 256: Flatworms and Friends Today’s Learning Goals: After completion of the laboratory students should be able to: 1. Identify representatives from 3 Classes within Phylum Platyhelminthes, 2. Understand the disadvantages of an acoelomate body plan and how flatworms deal with these disadvan...

BI 256: Flatworms and Friends Today’s Learning Goals: After completion of the laboratory students should be able to: 1. Identify representatives from 3 Classes within Phylum Platyhelminthes, 2. Understand the disadvantages of an acoelomate body plan and how flatworms deal with these disadvantages. 3. Understand the different muscle arrangement and locomotion patterns of the flatworms. 4. Identify members of Phylum Gastrotricha. 5. Identify representatives from two different Rotifer Phyla 6. Identify key features of the groups observed in lab. Outline Phylum Platyhelminthes FLATWORMS Body plan: Bilaterally symmetrical, Acoelomate Lifestyle: Free living / parasitic Locomotion: (cilia; muscles: dorsoventral, longitudinal, circular) Class Turbellaria (e.g. Dugesia sp.) Class Trematoda (Fasciola hepatica) Class Cestoda (Taenia sp.) Platyhelminthes Background What is a flatworm? Simple vermiform metazoan Triploblastic, acoelomate, bilaterally symmetrical animals Blind gut; no definitive anus Usually flattened dorso-ventrally Body packed with parenchyma (mesenchyme) Cephalized! The anterior end of the body carries sense organs The body is packed with parenchyma Free-living and parasitic lineages The Phylum is traditionally divided into four (4) classes. We will look at three classes: Turbellaria, Trematoda and Cestoda. Class: Turbellaria (e.g. Dugesia sp.) Phylum Platyhelminthes FLATWORMS Muscles: dorso-ventral longitudinal Circular Locomotion: Primarily by cilia/mucous; Minor muscular Class: Trematoda (Fasciola hepatica) All trematodes are parasitic flukes Most adults are endoparasites of vertebrates Often complicated lifecycles Adaptations for parasitism: Penetration glands Glands to produce cyst material Hooks and suckers for adhesion Increased reproductive capacity Our representative is Fasiola hepatica – sheep liver fluke  Miracidia - free swimming infect snail intermediate hosts Rediae -In snail tissue, have mouths may form more redia or cercaria Cercariae – Free swimming, encysts on water plants as metacercariae Class Cestoda (Taenia sp.) All Cestodes are vertebrate digestive tract parasites Commonly called “tapeworms” some may exceed 20m Almost all require two hosts Definitive host (vertebrate) Intermediate host (may be invertebrate or vertebrate) Lost “head and gut” Our representative is Taenia sp. Class Cestoda Three body regions: Scolex Suckers and hooks for attachment to host Neck Zone of proliferation Strobila Chain of reproductive proglottids No external motile cilia Body covered with microtriches Increase surface area for food absorbtion Flatworm to see/do: Observe live planaria Observe prepared slides Class Turbellaria: Dugusia Whole body & c.s. Class Trematoda: Fasciola hepatica Whole body & 3 larval forms Class Cestoda: Taenia sp. The “Friends” Common in pond samples not discussed much in lecture: Phylum Gastrotricha: (Fig 14.27, P317) Body plan: Bilaterally symmetrical, Acoelomate Key features: furcula, modified dorsal cuticle, ventral cilia Phylum Rotifera: “Wheel Animalcules” Body plan: Pseudocoelomate Lifestyle: Free living, Planktonic Classes: Bdelloidea and Monogononta Key features: -3-regions, - Parts: toes, corona, trophi, mastax, Gnathifera Gastrotricha Microscopic, aquatic, worm-like Glides along substrate Three main characteristics: 1) Furcula (forked tail) 2) Modified cuticular surface dorsal spines or scales 3) Cilia restricted to the ventral side Rotifera small microscopic animals, competing with the Gastrotrichs as some of the smallest animals. Bilaterally symmetrical pseudocoelomates “wheel bearer” Two distinguishing features: the corona, a ciliated anterior region locomotion and food collection. the trophi, complex jaws, housed within a muscular pharynx(mastax). Two most common classes Bdelloidea Monogononta Gastrotrichs and Rotifera to do Observe prepared slides Observe live specimens in depression slides  Flatworms and Friends: Lab Quiz Quiz will be written at start of next lab! We will start ASAP