How are worms different?

ALL WORMS are:INVERTEBRATES (no backbone)

PROTOSTOMES (blastopore mouth)

COELOM TYPES:

Flatworms = acoelomatesRound worms = PseudocoelomatesSegmented worms = coelomates

FLAT WORMS(PLATYHELMINTHES)

PLANARIAFLUKES

TAPEWORMS

FLATWORMSPlanaria

(Cross-eyed worm)

DIGESTIVE/CIRCULATORY SYSTEMS

Only one opening- in and out through mouth

One big cavity for digestion and circulation= Gastrovascular cavity

MOUTH in middle on VENTRAL SURFACE

NERVOUS SYSTEM

CEPHALIZATION-CEREBRAL GANGLIA with 2 VENTRAL NERVE CORDS

REGENERATION(Ability to regrow lost body parts)

REPRODUCTION

HERMAPHRODITES- Sexual reproduction with partner

Can also use REGENERATION for ASEXUAL reproduction

FLATWORMSPLANARIA

• Free living• Digestive cavity with one opening/mouth in middle of

body• Open circulatory system (shared Gastrovascular cavity)• Flame cells for excreting nitrogen waste

and excess water• Cephalization-Cerebral ganglia with 2 nerve cords• Hermaphrodites with sexual reproduction

(asexual reproduction using regeneration)• Eye spots sense light and dark• No protective covering

FLATWORMSFLUKES

DIGESTIVE/CIRCULATORY,NERVOUS, & EXCRETORY Similar to Planaria

MOUTH at anterior end

SUCKERS (anterior and ventral) help it hold on and suck blood

REPRODUCTIONCOMPLICATED LIFE CYCLES

need 2 hosts to complete life cycleEX: BLOOD FLUKE Adult-human

larva-snails

Most HERMAPHRODITES- Sexual reproduction with partner

FLATWORMSFLUKES

• Flattened leaf shape• Digestive cavity with one opening /mouth at anterior end• Open circulatory system (Gastrovascular cavity)• Flame cells for excreting nitrogen waste

and excess water• Cephalization -Cerebral ganglia with 2 nerve cords• Hermaphrodites with sexual reproduction• NO Eyes• Parasitic with 2 suckers (anterior & ventral) for

attaching to host• Requires 2 hosts to complete life cycle• TEGUMENT for protection from host

FLATWORMSTAPEWORMS

Dog tapeworm

NO DIGESTIVE SYSTEMAbsorbs nutrients through its tegument

EXCRETORY & NERVOUS similar to other flatworms

SCOLEX with hooks and suckers at anterior end to help worm attach and hold on

REPRODUCTIONCOMPLICATED LIFE CYCLES

need 2 hosts to complete life cycleEX: BEEF TAPEWORM Adult-human

larva-cow

HERMAPHRODITES- Proglottids exchange sperm between different worms or within same worm

REPRODUCTIONAdults produce hermaphroditic

reproductive segments containing eggs that are released in feces calledPROGLOTTIDS

FLATWORMSTAPEWORMS

• NO digestive system/nutrients absorbed through tegument

• Flame cells for excreting nitrogen waste and excess water• Cerebral ganglia with 2 nerve cords• Parasitic with hooks & suckers (scolex) for attachment in

host• Tegument for protection from host immune system and

digestive juices• Hermaphrodites with sexual reproduction

Use PROGLOTTIDS to reproduce• No Eyes

ROUND WORMSEx: Ascaris

• Digestive system - Complex with 2 openings • Nephridia for excreting nitrogen waste

and excess water• Cephalization-Cerebral ganglia with 2 nerve cords• Sexual reproduction with separate sexes- male and

female• No eyes spots • CUTICLE- for protection from host digestive juices

and immune system• Most are parasitic

SEGMENTED WORMSEarthworms & Leeches

• Cephalization- cerebral ganglia with 1 ventral nerve cord

• Closed circulatory system • Nephridia excrete nitrogen waste and regulate water• Complex digestive system with 2 openings• CUTICLE- for protection• Hermaphrodites- Sexual reproduction with a partner• Most free living/Leeches only parasitic group