SYSTEMATICS

• Phylum Platyhelminthes


  Flatworms
• Platyhelminthes


  • Bilateral symmetry
  • Acoelomate - Lack a body cavity(coelom)
  • 3 Layers: endoderm,ectoderm,mesoderm
  • Unsegmented
  • Gastrovascular cavity
  • Mouth - one opening (pharynx tube)
  • Cephalization -nerves and sense organs at anterior end
  • Definite head and body organs
  • Do not have circulatory and respiratory organs
  • Protonephridia present
  • Composed of networks of tubules with ciliated structures called flame bulbs
  • Movement via contracting muscles or underside cilia
  • Hermaphrodites
  • Regeneration
• Class Turbellaria


  Includes marine worms & planarians, most free living
• Planarian


  • Movement: cilia on ventral surface/ muscle contractions
  • Digestive System: Feeding: suction of pharynx (middle of body), Gastrovascular cavity, No Respiratory/ Circulatory system: diffusion
  • Nervous System: Ganglia (simple brain), 2 Nerve cords, Eyespot(senses light)
  • Excretory System: Flame cells- remove fluid waste
  • Reproduction: Sexual- hermaphrodite, cross fertilize, Asexual- regeneration
• Planarian body parts


  • Eyespot
  • Intestine
  • Pharynx
  • Mouth
• Class Trematoda


  Flukes (parasitic), Leaf-shaped, Sucks blood, cell fluids
• Trematoda examples


  • Sheep liver fluke: 2 hosts: sheep, snail, Larva develop inside snail, Sheep eats grass with larva
  • Blood fluke Schistosoma causes disease Schistosomiasis
• Trematoda body parts


  • Oral sucker
  • Ventral sucker
  • Fasciola hepatica ova
• Class Cestoda


  Tapeworm, Parasite
• Cestoda


  • Body: absorbs nutrients; tegument/cuticle prevents parasite from being digested by host
  • Scolex - hooks and suckers that attach to intestinal wall (no mouth)
  • Proglottid - segment containing reproductive organs
• Cestoda examples


  • Dipylidium caninum ova, Dipylidium caninum mature, Dipylidium caninum ripe
  • Hymenolepis diminuta scolex, Hymenolepis diminuta immature, Hymenolepis diminuta mature, Hymenolepis diminuta gravid segment
  • Schistosoma japonicum male and female in copula, Schistosoma japonicum female, Schistosoma japonicum male, Schistosoma japonicum miracidium, Schistosoma japonicum cercariae, Schistosoma japonicum ova
  • Taenia solium scolex, Taenia solium cyst
• Phylum Annelida


  Segmented worms
• Annelida


  • Annelida means "little rings," referring to the annelid body's resemblance to a series of fused rings
  • Triploblastic coelomate worms with a complete gut
  • Body wall and internal organs are segmented (except digestive tract)
  • Closed circulatory system (respiratory pigments may include hemoglobin, chlorocruorin and hemerythrin)
  • Most possess metanephridia; some protonephridia
  • Head is composed of a prostomium and peristomium
  • Nervous system well developed
  • With lateral, segmentally arranged epidermal chaetae
  • Hermaphroditic
• Annelida examples


  • Spirobranchus giganteus
• Class Errantia


  Freely moving polychaetes, Mostly marine, Head distinct and bearing eyes and tentacles, Clitellum absent
• Errantia


  • Most segments with parapodia (lateral appendages) bearing tufts of many setae
  • Sexes usually separate; gonads transitory; asexual budding in some
• Errantia examples


  • Nereis, Aphrodita, Glycera
• Nereis body part


  • Parapodium, Chaetae
• Class Sedentaria


  Worms with polychaete and oligochaete body plans that live in tubes or burrows, Most sedentary tube and burrow dwellers are particle feeders, using ciliary or mucoid methods of obtaining food
• Order Clitellata: Family Lumbricidae


  Group members share a unique reproductive structure called a clitellum, Clitellum is a ring of secretory cells in the epidermis that appears on the worm's exterior as a fat band around the body about one-third of the body length from the anterior end, Lacks parapodia, All hermaphroditic
• Earthworm body parts


  • Nephridium, Esophagus, Chaetae, Seminal vesicle
• Order Clitellata: Family Hirudinidae


  Body with fixed number of segments (normally 34; 15 or 27 in some groups) with many annuli (rings), Oral and posterior suckers usually present, Clitellum present; no parapodia, Coelom closely packed with connective tissue and muscle, Hermaphroditic, Terrestrial, freshwater, and marine
• Hirudinidae examples


  • Hirudo, Placobdella, Macrobdella
• Leech body parts


  • Oral sucker, Posterior sucker
• Phylum Nematoda


  Roundworms
• Nematoda


  • Pseudocoelom (false cavity): located between endoderm and mesoderm, Fluid filled (O2, CO2, nutrients diffuse into fluid)
  • Their most distinctive feature is a tough cuticle that coats their body which undergo ecdysis/ molting
  • Cylindrical body with tapered ends
  • Lack circulatory system
  • Nutrients are transported throughout the body via fluid in the hemocoel
  • Unique sensory amphids or phasmids: Amphids – sensory organ at the anterior, Phasmids - sensory organ at the posterior
  • Two openings: mouth and anus (tube in a tube)
  • Free living (most): Found in most aquatic habitats, in the soil, in the moist tissues of plants, and in the body fluids and tissues of animals, Feed on bacteria, fungi, other nematodes, organic matter
  • Parasitic: Beneficial as a natural pest control (worm enters insect larva > worm releases bacteria > bacteria multiply/poison > larva dies), Harmful: Reduce plant vigor, Infected root
• Nematode parasites


  • Roundworms, Hookworms, Pinworms, Trichina Worms, Filarial Worms
• Ascaris life cycle


  Immature worms hatch from eggs in stomach > Intestine(larva) > to lungs, Coughed up, swallowed, return to intestine(mature to adult), Eggs exit through feces
• Polychaete


  A type of annelid worm that lives in marine environments and is characterized by having many bristles on its body
• Annelid


  A phylum of worms that are known for their segmented bodies, including earthworms, leeches, and polychaetes
• Segmented


  A characteristic of annelids, including Spirobranchus giganteus, in which the body is divided into a series of rings or segments
• Hermaphroditic


  A characteristic of Spirobranchus giganteus in which it has both male and female reproductive organs