WormsWorms Flatworms – Phylum PlatyhelminthesFlatworms – Phylum Platyhelminthes Roundworms – Phylum NematodaRoundworms – Phylum Nematoda Segmented worms – Phylum AnnelidaSegmented worms – Phylum Annelida

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Flatworms(Phylum Platyhelminthes)

Planarian wormPlanarian worm

Tapeworm headTapeworm head

Each segment a complete reproduction Each segment a complete reproduction kit testes and ovarieskit testes and ovaries

Absorbs nutrients from juices in gutAbsorbs nutrients from juices in gut Makes millions of eggs a day.Makes millions of eggs a day. Adds segments to tail end….Adds segments to tail end….

Tapeworms in humans can Tapeworms in humans can grow more than 33 ft. grow more than 33 ft. long….long….

Tapeworm life cycleTapeworm life cycle

RoundwormsRoundworms(Phylum Nematoda)(Phylum Nematoda) Among most numerous of all animals.Among most numerous of all animals. Rotting apple can contain as many as 90,000 Rotting apple can contain as many as 90,000

roundworms.roundworms. Cubic meter of garden soil can contain more Cubic meter of garden soil can contain more

than 1,000,000 nematodes.than 1,000,000 nematodes.

Roundworm anatomyRoundworm anatomy

Trichinella worm

Filarial roundworms can Filarial roundworms can cause elephantiasiscause elephantiasis

Transmitted by Transmitted by biting insects, biting insects, esp. esp. mosquitoes.mosquitoes.

Block passage Block passage of fluids in of fluids in lymph vessels, lymph vessels, causing causing inflammationinflammation

http://www.stanford.edu/group/parasites/ParaSites2006/Lymphatic_filariasis/Images/elephantiasis_2.GIF

Ascaris wormAscaris worm Parasitic nematode that Parasitic nematode that

infects pigs and people.infects pigs and people. Typically found in tropical Typically found in tropical

and sub-tropical areas and sub-tropical areas with poor sanitation.with poor sanitation.

Largest intestinal Largest intestinal roundworm, and most roundworm, and most common worm infection common worm infection for humans worldwide.for humans worldwide.

Infestation can cause Infestation can cause morbidity, sometimes morbidity, sometimes death by blocking death by blocking digestive system.digestive system.

Ascaris life cycleAscaris life cycle

1.1. Adult worms live in Adult worms live in small intestine.small intestine.

2.2. Eggs passed through Eggs passed through feces (200,000/day).feces (200,000/day).

3.3. Fertilized eggs develop Fertilized eggs develop into embryos.into embryos.

4.4. Eggs swallowed via Eggs swallowed via unclean food or fingers.unclean food or fingers.

5.5. Larvae hatch, travel Larvae hatch, travel through blood to lungs.through blood to lungs.

6.6. Larvae mature in lungs, Larvae mature in lungs, climb/coughed into climb/coughed into throat, where throat, where swallowed. Pass into swallowed. Pass into small intestine.small intestine.

Ascaris-filled intestineAscaris-filled intestine

Segmented worms (Phylum Segmented worms (Phylum Annelida)Annelida)

““annelus” = little ringannelus” = little ring Worms with bodies Worms with bodies

divided into divided into segments.segments.

Most segments Most segments similar, but may be similar, but may be modified to perform modified to perform special functions – special functions – eyes, antennae, eyes, antennae, appendages, etc.appendages, etc.

LeechesLeeches

External parasites External parasites that suck blood from that suck blood from hosts.hosts.

Powerful suckers Powerful suckers help cling to hosts. help cling to hosts. Some have sharp Some have sharp jaws to cut through jaws to cut through skin.skin.

Some anesthetize Some anesthetize skin so host doesn’t skin so host doesn’t feel bite!feel bite!

Medicinal leechesMedicinal leeches Commonly used in Middle Commonly used in Middle

Ages for bloodletting Ages for bloodletting (draining blood to cure (draining blood to cure illnesses).illnesses).

Used in modern medicine Used in modern medicine to reduce swelling after to reduce swelling after surgeries.surgeries.

Giant Palouse Earthworm lives in Eastern WA and Idaho.Giant Palouse Earthworm lives in Eastern WA and Idaho. Can grow up to 3 feet long!Can grow up to 3 feet long!

EarthworEarthworm m AnatomyAnatomy

How do How do earthworms do earthworms do “the nasty”?“the nasty”? Earthworms are Earthworms are

hermaphroditic (have both hermaphroditic (have both male and female male and female reproductive organs)reproductive organs)

Two worms attach to each Two worms attach to each other and exchange sperm, other and exchange sperm, then separate.then separate.

Each worm excrete eggs Each worm excrete eggs onto skin near clitellum, onto skin near clitellum, which secretes thick band of which secretes thick band of mucous.mucous.

Worm slips out of mucous Worm slips out of mucous band, which hardens until band, which hardens until fertilized eggs hatch.fertilized eggs hatch.

The End The End (Thank G-d!!)(Thank G-d!!)

Let’s all go home and forget this ever Let’s all go home and forget this ever happened…..happened…..