2Flatworms: Phylum Platyhelminthes Soft and FlatTissues and Internal Organ Systems3 embryonic germ layers (Ecto, Meso, & Endoderm)Bilateral symmetryCephalizationAcoelomates-without coelom (no fluid-filled body cavity)
4FeedingCarnivoreScavengerParasiticMouth/anus with pharynx (muscular tube that moves food and waste)Gastrovascular cavity – digestion/absorptionParasites – simple or no digestive system b/c feed on blood, tissue fluids, or cell pieces of host
5Respiration, Circulation, Excretion Diffusion (transport O2 and nutrients) through body wallsFlame cells – remove excess water and wasteConnected to pores in the skin
6Response Ganglia – controls N.S. (nerve cell cluster) Eyespot – detects light changesSome have specialized cells to detect chemicals, food, etc.
8Movement Cilia on epidermal cells for gliding Muscle cells for twisting/turning
9Reproduction Hermaphrodites Sexual by 2 worms joining, exchanging sperm, and each lay eggsInternal fertilizationAsexual by fission (organism splits in 2 and each half grows new parts)
10Figure 27–3 The Anatomy of a Flatworm GangliaEyespotFreshwater 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.HeadNerve cordsGastrovascular cavityFlatworms 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.Excretory systemOvaryTestesMouthPharynxMost flatworms are hermaphrodites, having male reproductive organs (testes) and female reproductive organs (ovaries) in the same organism.Flame cellExcretory tubule
11TurbellariansFlukesTapewormsClasses of Flatworms:
19Figure 27-5Primary host (human)Flukes mature and reproduce sexually in the blood vessels of human intestines. Embryos are released and passed out with feces.Intermediate host (snail)AdultflukeHumanintestineEmbryoCiliatedlarvaTailedlarvaAfter asexual reproduction, new larvae are released from the snail into the water. They then infect humans, the primary host, by boring through their skin.Once in the water, embryos develop into swimming larvae that infect an intermediate host (snail).
20Class Cestoda: Tapeworms ParasiticLives in intestinesLong and flatScolex-head with suckers or hooksProglottids-body segments
21Cow/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.
22Roundworms: Phylum Nematoda UnsegmentedMost are free-livingDigestive tract with two openings – mouth and anusPseudocoelom-false body cavity
23Feeding Most are carnivores Use mouth parts and spines to catch food Hook Worms
24Respiration, Circulation, Excretion Diffusion through body walls
25Response Simple nervous system Nerves run body length from Ganglia in headSimple sense organs to detect chemicals from prey or hosts
26Movement Hydrostatic skeleton Muscles and fluid in the pseudocoelom work together to produce movement
29Trichinella Trichinosis Cysts are ingested from eating animal muscle tissueFemales burrow into intestinal wallLarvae travel to organs via bloodstream and form cysts
30Filarial Worms Live in blood and lymph vessels Transmitted by mosquitoesCan block the movement of fluidsElephantiasis
31Ascaris 1. Eggs hatch in intestines 2. Larvae burrow into bloodstream to lungs3. Travel to air passages, then swallowed4. Carried to the intestines and mature5. Eggs released via fecesSpread by eating improperly washed vegetables (foods)
33Hookworms ¼ of the human population infected with hookworms Eggs hatch outside body and develop in soilUse sharp toothlike plates and hooks to burrow into skin and enter bloodstreamTravel to lungs and then intestinesSuck blood causing weaknessDon’t walk barefoot outside!!!
35Annelids: Phylum Annelida --Segmented worms with a coelom (body cavity) that is lined with mesoderm
36Feeding and digestion Filter feeders to predators Earthworm Full Digestive Tract: mouth pharynx esophagus crop gizzard intestine anusCrop- store foodGizzard- grind food
37Circulation Closed system, 2 major blood vessels Dorsal blood vessel: tail head (pumps like heart)Ventral blood vessel: head tail
38Respiration and Excretion Skin (moist due to mucus secretion) - landGills - aquaticExcretion-Nephridia - filter out fluid/liquid wasteAnus – solid waste
39Movement- Reproduction- Hydrostatic skeleton Longitudinal muscles – short and fatCircular muscles – long and thinSetae- brush hair-like projectionsReproduction-Mostly sexual, some hermaphrodites, some separate sexesClitellum-thick band secretes mucus ring after 2 worms exchange sperm for fertilizationMucus ring slips off and forms protective cocoonhatching