Transcript Bio Worms
WORMS Flatworms: Phylum Platyhelminthes Soft and Flat Tissues and Internal Organ Systems 3 embryonic germ layers (Ecto, Meso, & Endoderm) Bilateral symmetry Cephalization Acoelomates-without coelom (no fluidfilled body cavity) Feeding •Carnivore •Scavenger •Parasitic Mouth/anus with pharynx (muscular tube that moves food and waste) Gastrovascular cavity – digestion/absorption Parasites – simple or no digestive system b/c feed on blood, tissue fluids, or cell pieces of host Respiration, Circulation, Excretion Diffusion (transport O2 and nutrients) through body walls Flame cells – remove excess water and waste Connected to pores in the skin Response Ganglia – controls N.S. (nerve cell cluster) Eyespot – detects light changes Some have specialized cells to detect chemicals, food, etc. Movement Cilia on epidermal cells for gliding Muscle cells for twisting/turning Reproduction Hermaphrodites Sexual by 2 worms joining, exchanging sperm, and each lay eggs Internal fertilization Asexual by fission (organism splits in 2 and each half grows new parts) Figure 27–3 The Anatomy of a Flatworm Ganglia Eyespot Head Nerve cords Gastrovascular cavity Flatworms use a pharynx to suck food into the gastrovascular cavity. Digested food diffuses from the cavity into other cells of the body. Eyespots in some species detect light. Mouth Excretory system Freshwater flatworms have simple ganglia and nerve cords that run the length of the body. The excretory system consists of a network of tubules connected to flame cells that remove excess water and cell wastes. Ovary Testes Pharynx Flame cell Excretory tubule Most flatworms are hermaphrodites, having male reproductive organs (testes) and female reproductive organs (ovaries) in the same organism. Classes of Flatworms: Turbellarians Flukes Tapeworms Class Turbellaria: Turbellarians Free-living Marine or fresh water Not Parasitic Ex. Pseudobiceros gloriosus Tropical free-living flatworm (non-parasitic) Ex. Planaria Cross-eyed; fresh water free-living flatworm (non-parasitic) Class Trematoda: Flukes Parasitic Infect internal organs of hosts Blood flukes – travel to intestines of host Some have Multiple Hosts Ex. Blood Fluke (not free-living) Parasite that matures in human blood vessels Schistosoma mansoni (has multiple hosts: Snail=intermediate host Human=primary host) Figure 27-5 Primary host (human) Intermediate host (snail) Human Adult intestine fluke Flukes mature and reproduce sexually in the blood vessels of human intestines. Embryos are released and passed out with feces. Embryo After asexual reproduction, new larvae are released from the snail into the water. They then infect humans, the primary host, by boring through their skin. Tailed Ciliated larva larva Once in the water, embryos develop into swimming larvae that infect an intermediate host (snail). Class Cestoda: Tapeworms Parasitic Lives in intestines Long and flat Scolex-head with suckers or hooks Proglottids-body segments • Cow/Fish (intermediate host) consumes food or water w/ zygotes. • Hatch to larvae and burrow into muscles as cysts (protected) •human eats meat not fully cooked and larvae activated to grow to adult in human intestines. Roundworms: Phylum Nematoda Unsegmented Most are free-living Digestive tract with two openings – mouth and anus Pseudocoelom-false body cavity Feeding Most are carnivores Use mouth parts and spines to catch food Hook Worms Respiration, Circulation, Excretion Diffusion through body walls Response Simple nervous system Nerves run body length from Ganglia in head Simple sense organs to detect chemicals from prey or hosts Movement Hydrostatic skeleton Muscles and fluid in the pseudocoelom work together to produce movement Reproduction Sexual Internal fertilization Separate genders Human Disease --Parasitic Roundworms Trichinosis-Causing Worms Filarial Worms Ascarid Worms Hookworms Trichinella Trichinosis Cysts are ingested from eating animal muscle tissue Females burrow into intestinal wall Larvae travel to organs via bloodstream and form cysts Filarial Worms Live in blood and lymph vessels Transmitted by mosquitoes Can block the movement of fluids Elephantiasis Ascaris 1. Eggs hatch in intestines 2. Larvae burrow into bloodstream to lungs 3. Travel to air passages, then swallowed 4. Carried to the intestines and mature 5. Eggs released via feces • Spread by eating improperly washed vegetables (foods) Hookworms ¼ of the human population infected with hookworms Eggs hatch outside body and develop in soil Use sharp toothlike plates and hooks to burrow into skin and enter bloodstream Travel to lungs and then intestines Suck blood causing weakness Don’t walk barefoot outside!!! Annelids: Phylum Annelida --Segmented worms with a coelom (body cavity) that is lined with mesoderm Feeding and digestion Filter feeders to predators Earthworm Full Digestive Tract: mouth pharynx esophagus crop gizzard intestine anus Crop- store food Gizzard- grind food Circulation Closed system, 2 major blood vessels Dorsal blood vessel: tail head (pumps like heart) Ventral blood vessel: head tail Respiration and Excretion RespirationSkin (moist due to mucus secretion) - land Gills - aquatic ExcretionNephridia - filter out fluid/liquid waste Anus – solid waste Movement Hydrostatic skeleton Longitudinal muscles – short and fat Circular muscles – long and thin Setae- brush hair-like projections ReproductionMostly sexual, some hermaphrodites, some separate sexes Clitellum-thick band secretes mucus ring after 2 worms exchange sperm for fertilization Mucus ring slips off and forms protective cocoonhatching Classes of Annelids Class Oligochaeta: Oligochaetes- Earthworms Few setae on each segment Soil or fresh water Class Hirudinea: Leeches External parasites Suck blood and body fluids of host Medicinal Uses Reduces swelling and prevents clotting Class Polychaeta: Polychaetes Sandworms, bloodworms Marine Paired paddle-like appendages w/ setae Live in coral reefs, sand, mud What do you think caused this marking? Worm? Bacteria? Virus? Fungus? Hickey? Ringworm Not caused by a worm! Fungal infection Can occur on any part of body Contact with infected people, animals, soil, etc. Medically called Tinea Earthworm Dissection External View Internal Structure Pharynx Aortic Arches Seminal Vesicle Seminal Receptacle Septum Crop Gizzard Intestine Ventral Nerve Cord Dorsal Blood Vessel