The Worms Phylum Platyhelminthes Phylum Nemertea Phylum Nematoda Phylum Annelida

Bilateral Symmetry One way to cut and get 2 identical halves Front (anterior) and rear (posterior) Back (dorsal) and belly (ventral) More active in pursuit of prey

Platyhelminthes - Flatworms Dorsoventrally flattened Simple Central Nervous system Muscular system, Reproductive system - True organs Singular opening for gut

20,000 Species of Flatworms Turbellarians - Free-living carnivores, seen most in marine habitats Flukes (Trematodes) – largest group, parasites Tapeworms (cestodes) – live in intestines.

Ribbon Worms (Nemertea) Sac Gut digestive tract (mouth, gut) Circulatory system/Hermaphrodites Proboscis – used to entangle prey Feed on worms and crustaceans

Nematodes (some – roundworms) Live in sediment or tissues of marine organisms (parasitic) Cylindrical body, pointed at both ends. Larva found in the flesh of many fish –Infection of humans from eating raw or under cooked fish

Annelida – segmented worms Includes earthworms and many marine worms Polychaetes – marine annelids. –Each segment has parpodia with setae at the ends. –Closed circulatory system –Most carnivores - Nereis

More Annelids Oligochaetes –Marine earthworms, found in mud and sand Leeches (Hirudinea) –Most are freshwater – sucker at ends

Brachiopoda (not a worm) Lamp shell Two valves, dorsal and ventral Lophophore, unique feeding structure – like two ciliated, coiled arms

The Christmas Tree Worm The Christmas tree worm, Spirobranchus giganteus, is a Christmas tree-shaped serpulid tube-dwelling worm with magnificent twin spirals of plumes used for feeding and respiration. This cone- shaped worm is one of the most widely recognized sedentary polychaete worms.