Phyla Platyhelminthes, Nemertea, Nematoda, Annelida, Sipuncula, & Echiura

The Worms

I) Worms

A) Bilateral SymmetryB) True organs & organ systemsC) All have complete digestive tracts except for

flatwormsD) Mesoderm (middle cell layer)

1) Muscles, Reproductive Organs, & Other Organs

II) Phylum Platyhelminthes

A) AKA: Flatworms

B) ~20,000 species

C) Central Nervous System1) Brain

2) Simple Nerve Aggregation

D) Turbellarians1) Free-swimming carnivores

II) Phylum Platyhelminthes

E) Flukes (trematodes)1) Parasites: Feed on

blood, intestines, tissues

F) Tapeworms (cestodes)

III) Phylum Nemertia

A) AKA: Ribbon Worms

B) ~900 known species

C) Primitive circulatory system

D) Proboscis1) Long, flesh tube used to

entangle prey

2) Predators

E) Longest invertebrate on Earth

1) Over 100 feet long

IV) Phylum NematodaA) AKA: Roundworms

B) 10,000 – 25,000 known species1) Estimated to be ½

million species

2) Undercounted

C) Live in rich sediment or are parasitic

D) Hydrostatic skeleton

V) Phylum Annelida

A) AKA: Segmented Worms

B) ~20,000 known speciesC) SegmentedD) Gut lies in cavity known

as coelomE) Hydrostatic skeletonF) Closed Circulatory

SystemG) Respiration

1) Through skin – smaller2) Gills – larger

V) Phylum Annelida

H) Class Polychaeta1) AKA: Bristle Worms

2) Parapodia: movement

3) Setae: sharp bristles

4) Predators & Suspension Feeders

V) Phylum Annelida

I) Class Oligochaetes1) AKA: Earthworms &

Relatives

2) Suspension Feeders

3) No Parapodia

V) Phylum Annelida

J) Class Hirudinea1) AKA: Leeches

2) Suspension Feeders

3) Suckers on each end

4) No Parapodia

VI) Phylum SipunculaA) AKA: Peanut WormsB) ~320 known speciesC) UnsegmentedD) Retractable tentacles

for feeding (deposit feeders)

VII) Phylum Echiura

A) AKA: Spoon Worms

B) ~135 known species

C) Unsegmented

D) Non-retractable proboscis (deposit feeders)