Flatworm Characteristics --Flat bodies (gases move by diffusion) --bilateral symmetry --gastrovascular cavity --some flatworms are parasitic, some are freeliving --they have anterior and posterior heads and exhibit cephalization

Types of Flatworms (planarian, tapeworm, fluke) Planarian (also known as Dugesia)--lives in freshwater --mostly a scavenger, also feeds on protists --hermaphrodites --has a simple brain (ganglia) and nervous system, plus 2 eyespots --they can regenerate (regrow parts)

Anatomy of the Planarian Brain (ganglia) - planarian can process information about their environment Pharynx - used for suckling food in (the mouth is at the end of the pharynx) Eyespot - simple eye, can detect light Intestine - digestion (does not have an anus)

Tapeworms --parasitic worms that live in the digestive system.Diffuse nutrients into body --they have segmented bodies (each segment is called a proglottid) --each proglottid is a reproductive organ --tapeworms can grow very long (40 feet!) --attach to the intestine with hooks and suckers on the head

Flukes --most have complex life cycles involving more than one host --Schistosoma (blood fluke) spends part of its life in a snail, humans get infected when they wade in the water containing the snails, the larva then invade the human's blood vessels --eggs are passed thru human feces into water where the snail is infected

Roundworms --have a complete digestive tract Ascaris -common roundworm infection in humans and dogs Trichinella -roundworms that invade muscle tissue, get by eating undercooked pork Vinegar eel - free living roundworm

Roundworms- Ascaris

Trichinella worm

Hookworm