Phylum CtenophoreThe comb jelliesLess than 100

speciesRadial symmetry8 rows of ciliary

combs, that beat in waves

Marine WormsOctober 31st, 2014

Phylum Platyhelminthes

Flatworms

-20,000 species

-flattened

-bilaterally symmetry

-central nervous system with simple brain

-organ and organ system

-some free-living

-some parasitic—live in or on other organisms and harm them (flukes and tapeworms)

planaria

Flatworms

Flatworms

Flatworms

Internal parasites

Flatworms

scolex

Worm body

tapeworms

Flatworms

Phylum NemerteaRibbon worms

• Look like long flatworms but more

complex

• Complete digestive tract

• Circulatory system

• Proboscis –long fleshy tube used to

entangle prey.

• 900 species-mostly marine.

• In all oceans, mostly shallow

temperate waters

Ribbon worms

Phylum Nematoda

Roundworms

• Rarely seen-25,000 sp.

• Some parasitic, some

not

• Small, cylindrical

bodies, pointed at both

ends

• Live in sediments, eat

bacteria

Phylum Annelida

Segmented worms

Phylum Annelida

Phylum AnnelidaExamples: polychaete worms,

earthwormBilateral symmetryAdvanced marine worms

Closed circulatory systemOrgan organizationLarger ones have gillsMore advanced muscles system

Segmented bodiesOften live in tubes of mucus,

protein, seaweed, mud, sand, shells20,000 species

Symmetry

Radial

Bilateral

Segmented worms

Annelida

Segments: a series of compartments

Parapodia: each segment has flattened extensions

Setea: stiff hair-like projections. Project from parapodia and are connected to internal muslces. Allow for contractions and movement.

Annelida

Annelida

Annelida

Annelida

Annelida