Platyhelminthes

Cards (13)

  • PLATYHELMINTHES from Latin, platy - ‘flat’ + Greek helminth ‘worm’.
  • Usually flattened dorsoventrally, triploblastic, acoelomate
    • Unsegmented worms, bilaterally symmetrical; Somewhat cephalized; Epidermis may be cellular or syncytial (ciliated in some); rhabdites (secrete mucus)
    • Sense organs include statocysts (organs of balance) and ocelli.
  • Phylum Platyhelminthes Flatworms ; bilateral acoelomates . More than 34,000 species
  • Class Turbellaria
    Mostly free living and aquatic; external surface usually ciliated ; predaceous; possess rhabdites, protrusible proboscis, frontal glands, and many mucous glands; mostly hermaphroditic. Convoluta, Notoplana, Dugesia. More than 3,000 species.
  • Class Monogenea
    Monogenetic flukes ; mostly ectoparasites on vertebrates (usually on fishes; occasionally on turtles, frogs, copepods, squids); one life-cycle form in only one host; bear opisthaptor. Disocotyle, Gyrodactylus, Polystoma. About 1,100 species.
  • Class Trematoda
    Trematodes ; all are parasitic; several holdfast devices present ; have complicated life cycles sexual and asexual reproduction. More than 10,000 species.
  • Subclass Aspidogastrea
    Mostly endoparasites of molluscs; possess large opisthaptor; most lack an oral sucker Cotylaspis, Multicotyl. About 32 species.
  • Subclass Digenea
    Adults endoparasites have oral sucker in vertebrates; at least two different life-cycle forms in two or more hosts; and acetabulum. Schistosoma, Fasciola, Clonorchis. About 1,350 species.
  • Class Cestoidea
    All parasitic with no digestive tract ; have great reproductive potential species. tapeworms. About 3,500
  • Subclass Cestodaria
    Body not subdivided into ; tapeworms. About 3,500 proglottids; larva in crustaceans, adult in fishes About 15 species. Amphilina, Gyrocotyle.
  • Subclass Eucestoda
    True tapeworms; body divided into . Amphilina, Gyrocotyle. scolex, neck, and strobila; strobila composed of many proglottids ; both male and female reproductive systems in each proglottid; of vertebrates adults in digestive tract . Proteocephalus, Taenia, Echinococcus, Taeniarhynchus; Diphyllobothrium. About 1,000 species
  • PLATYHELMINTHES
    • Incomplete gut. Food digestion is extracellular.
    Protonephridia networks of fine tubules that run the length of the organism, along each of its sides.
    Flame cells removing waste materials through filtration
  • PLATYHELMINTHES
    Commissures points of union connect the nerve cords.
    Auricle sensory lobes may project from the side of the head, (chemoreceptors) that aid in food location.
    Monoecious with internal fertilization. Reproduce asexually by transverse fission.
    • The two (or more) animals that result from fission are called zooids