Phylum Ctenophore The comb jellies Less than 100 species Radial symmetry 8 rows of ciliary combs, that beat in waves

October 31 st, 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 Flatworm s

Internal parasites Flatworms

scolex Worm body tapeworms Flatworms

Phylum Nemertea Ribbon 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

Examples: polychaete worms, earthworm Bilateral symmetry Advanced marine worms Closed circulatory system Organ organization Larger ones have gills More advanced muscles system Segmented bodies Often live in tubes of mucus, protein, seaweed, mud, sand, shells 20,000 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