worms. flatworms: phylum platyhelminthes soft and flat soft and flat tissues and internal organ...
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WORMS WORMS
Flatworms: Phylum Flatworms: Phylum PlatyhelminthesPlatyhelminthes
Soft and FlatSoft and Flat Tissues and Internal Organ SystemsTissues and Internal Organ Systems 3 embryonic germ layers (Ecto, 3 embryonic germ layers (Ecto,
Meso, & Endoderm)Meso, & Endoderm) Bilateral symmetryBilateral symmetry CephalizationCephalization AcoelomatesAcoelomates-without coelom (no -without coelom (no
fluid-filled body cavity)fluid-filled body cavity)
FeedingFeeding
Mouth/anusMouth/anus with with pharynxpharynx (muscular tube that (muscular tube that moves food and waste)moves food and waste)
Gastrovascular cavityGastrovascular cavity – digestion/absorption – digestion/absorption ParasitesParasites – simple or no digestive system b/c – simple or no digestive system b/c
feed on blood, tissue fluids, or cell pieces of hostfeed on blood, tissue fluids, or cell pieces of host
•Carnivore
•Scavenger
•Parasitic
Respiration, Circulation, Respiration, Circulation, ExcretionExcretion
Diffusion (transport ODiffusion (transport O22 and and nutrients) through body wallsnutrients) through body walls
Flame cellsFlame cells – remove excess water – remove excess water and wasteand waste Connected to pores in the skinConnected to pores in the skin
Response Response
GangliaGanglia – controls N.S. (nerve cell – controls N.S. (nerve cell cluster)cluster)
EyespotEyespot – detects light changes – detects light changes Some have specialized cells to detect Some have specialized cells to detect
chemicals, food, etc.chemicals, food, etc.
MovementMovement
Cilia on epidermal Cilia on epidermal cells for gliding cells for gliding
Muscle cells for Muscle cells for twisting/turningtwisting/turning
ReproductionReproduction
HermaphroditesHermaphrodites Sexual by 2 worms Sexual by 2 worms
joining, exchanging joining, exchanging sperm, and each sperm, and each lay eggs lay eggs
Internal Internal fertilizationfertilization
Asexual by Asexual by fissionfission (organism splits in (organism splits in 2 and each half 2 and each half grows new parts)grows new parts)
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.
Most flatworms are hermaphrodites, having male reproductive organs (testes) and female reproductive organs (ovaries) in the same organism.
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 somespecies detect light.
Eyespot
Head
Gastrovascularcavity
Ganglia
Nervecords
Excretorysystem
Mouth Pharynx
Ovary
Testes
Excretorytubule
Flame cell
Figure 27–3 The Anatomy of a Flatworm
Classes of Flatworms: Classes of Flatworms: TurbellariansTurbellarians FlukesFlukes TapewormsTapeworms
Class Turbellaria: Class Turbellaria: TurbellariansTurbellarians
Free-livingFree-living Marine or fresh Marine or fresh
waterwater Not ParasiticNot Parasitic
Ex. Pseudobiceros gloriosusTropical free-living flatworm (non-parasitic)
Ex. PlanariaEx. Planaria Cross-eyed; fresh water free-living flatworm Cross-eyed; fresh water free-living flatworm
(non-parasitic)(non-parasitic)
Class Trematoda: FlukesClass Trematoda: Flukes ParasiticParasitic Infect internal organs Infect internal organs
of hostsof hosts Blood flukesBlood flukes – travel – travel
to intestines of hostto intestines of host Some have Multiple Some have Multiple
HostsHosts
Ex. Blood Fluke Ex. Blood Fluke (not free-(not free-
living)living)
Parasite that matures in human blood vessels
Schistosoma mansoni
(has multiple hosts:Snail=intermediate hostHuman=primary host)
Primary host (human)
Intermediate host(snail)
Human
intestine
Adult
fluke
Embryo
Ciliated
larvaTailed
larva
Flukes mature and reproduce sexually in the blood vessels of human intestines. Embryos are released and passed out with feces.
Once in the water, embryos develop into swimming larvae that infect an intermediate host (snail).
After asexualreproduction, newlarvae are releasedfrom the snail into the water. They then infect humans, the primary host, by boring through their skin.
Figure 27-5
Class Cestoda: Class Cestoda: TapewormsTapeworms
ParasiticParasitic Lives in intestinesLives in intestines Long and flatLong and flat ScolexScolex-head with -head with
suckerssuckers or or hookshooks ProglottidsProglottids-body -body
segmentssegments
• 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 Roundworms: Phylum NematodaNematoda
UnsegmentedUnsegmented Most are free-Most are free-
livingliving Digestive tract Digestive tract
with two openings with two openings – mouth and anus– mouth and anus
PseudocoelomPseudocoelom--false body cavityfalse body cavity
FeedingFeeding Most are carnivoresMost are carnivores Use mouth parts and Use mouth parts and
spines to catch foodspines to catch food
Hook Worms
Respiration, Circulation, Respiration, Circulation, ExcretionExcretion
Diffusion through body wallsDiffusion through body walls
Response Response
Simple nervous system Simple nervous system Nerves run body length from Nerves run body length from
Ganglia in head Ganglia in head Simple sense organs to detect Simple sense organs to detect
chemicals from prey or hostschemicals from prey or hosts
MovementMovement
Hydrostatic skeletonHydrostatic skeleton Muscles and fluid in the Muscles and fluid in the
pseudocoelom work together to pseudocoelom work together to produce movementproduce movement
ReproductionReproduction
SexualSexual Internal fertilizationInternal fertilization Separate gendersSeparate genders
Human DiseaseHuman Disease --Parasitic Roundworms--Parasitic Roundworms
Trichinosis-Causing WormsTrichinosis-Causing Worms Filarial WormsFilarial Worms Ascarid WormsAscarid Worms HookwormsHookworms
Trichinella Trichinella Trichinosis Trichinosis Cysts are ingested Cysts are ingested
from eating animal from eating animal muscle tissuemuscle tissue
Females burrow into Females burrow into intestinal wall intestinal wall
Larvae travel to Larvae travel to organs via organs via bloodstream and form bloodstream and form cystscysts
Filarial WormsFilarial Worms
Live in blood and Live in blood and lymph vesselslymph vessels
Transmitted by Transmitted by mosquitoesmosquitoes
Can block the Can block the movement of fluidsmovement of fluids
ElephantiasisElephantiasis
AscarisAscaris
1. Eggs hatch in 1. Eggs hatch in intestinesintestines
2. Larvae burrow into 2. Larvae burrow into bloodstream to lungsbloodstream to lungs
3. Travel to air passages, 3. Travel to air passages, then swallowedthen swallowed
4. Carried to the 4. Carried to the intestines and matureintestines and mature
5. Eggs released via feces5. Eggs released via feces
• Spread by eating improperly washed vegetables (foods)
HookwormsHookworms
¼ of the human population infected with ¼ of the human population infected with hookwormshookworms
Eggs hatch outside body and develop in Eggs hatch outside body and develop in soilsoil
Use sharp toothlike plates and hooks to Use sharp toothlike plates and hooks to burrow into skin and enter bloodstreamburrow into skin and enter bloodstream
Travel to lungs and then intestines Travel to lungs and then intestines Suck blood causing weaknessSuck blood causing weakness Don’t walk barefoot outside!!!Don’t walk barefoot outside!!!
--Segmented worms --Segmented worms with a with a coelomcoelom (body (body cavity) that is lined cavity) that is lined
with mesodermwith mesoderm
Annelids: Phylum Annelida
Feeding and digestionFeeding and digestion
Filter feeders to predatorsFilter feeders to predators Earthworm Earthworm
Full Digestive Tract: mouth Full Digestive Tract: mouth pharynxpharynx esophagusesophagus cropcrop gizzardgizzard intestineintestine anus anus
CropCrop- store food- store food GizzardGizzard- grind food- grind food
CirculationCirculation
Closed system, 2 major blood vesselsClosed system, 2 major blood vessels Dorsal blood vessel: tail Dorsal blood vessel: tail head (pumps head (pumps
like heart)like heart) Ventral blood vessel: head Ventral blood vessel: head tail tail
Respiration and Respiration and ExcretionExcretion
Respiration- Respiration- Skin (moist due to mucus secretion) - Skin (moist due to mucus secretion) -
landland Gills - aquaticGills - aquatic
Excretion- Excretion- Nephridia - filter out fluid/liquid wasteNephridia - filter out fluid/liquid waste Anus – solid wasteAnus – solid waste
Movement-Movement- Hydrostatic skeletonHydrostatic skeleton
Longitudinal muscles – short and fatLongitudinal muscles – short and fat Circular muscles – long and thin Circular muscles – long and thin
SetaeSetae- - brushbrush hair-like projectionshair-like projections
Reproduction-Reproduction- Mostly sexual, some hermaphrodites, Mostly sexual, some hermaphrodites,
some separate sexessome separate sexes ClitellumClitellum-thick band secretes mucus -thick band secretes mucus
ring after 2 worms exchange sperm for ring after 2 worms exchange sperm for fertilizationfertilization
Mucus ring slips off and forms Mucus ring slips off and forms protective cocoonprotective cocoonhatching hatching
Classes of Classes of AnnelidsAnnelids
Class Oligochaeta: Class Oligochaeta: OligochaetesOligochaetes- Earthworms- Earthworms
Few setae on each segment Few setae on each segment Soil or fresh waterSoil or fresh water
Class Hirudinea: LeechesClass Hirudinea: Leeches External parasitesExternal parasites Suck blood and body fluids of host Suck blood and body fluids of host Medicinal Uses Medicinal Uses
Reduces swelling and prevents clottingReduces swelling and prevents clotting
Class Polychaeta: Class Polychaeta: PolychaetesPolychaetes
Sandworms, Sandworms, bloodwormsbloodworms
Marine Marine Paired paddle-like Paired paddle-like
appendages w/ appendages w/ setaesetae
Live in coral reefs, Live in coral reefs, sand, mudsand, mud
What do you think caused this What do you think caused this marking?marking?
Worm?Worm? Bacteria?Bacteria? Virus?Virus? Fungus?Fungus? Hickey?Hickey?
RingwormRingworm
Not caused by a worm!Not caused by a worm! Fungal infection Fungal infection Can occur on any part of bodyCan occur on any part of body Contact with infected people, Contact with infected people,
animals, soil, etc.animals, soil, etc. Medically called Medically called TineaTinea
Earthworm Earthworm DissectionDissection
External ViewExternal View
Internal StructureInternal Structure
PharynxPharynx
Aortic ArchesAortic Arches
Seminal VesicleSeminal Vesicle
Seminal ReceptacleSeminal Receptacle
SeptumSeptum
CropCrop
GizzardGizzard
IntestineIntestine
Ventral Nerve CordVentral Nerve Cord
Dorsal Blood VesselDorsal Blood Vessel