3 Phyla of Worms Platyhelminthes Nematoda Annelida Flatworms Roundworms Segmented worms

What worms have in common Invertebrates Narrow bodies w/o legs HAVE tissues, organs, & organ systems Bilateral symmetry Head and tail ends Brain Sense organs – light and touch

Reproduction Hermaphrodites – both male and female; usually don’t self- fertilize Asexual – break into pieces and regenerate

Platyhelminthes Planarians Flukes Tapeworms

Platyhelminthes Most are parasites – get food from host Tapeworms live in digestive systems of host (many live in more than one host) Flukes can live in host’s liver

Planarians Nonparasitic Free-living Scavengers Predators Eyespots Smell Inserts feeding tube starts to break down food outside of body sucks up the food completes digestion inside body then waste goes out the feeding tube

Nematoda - Roundworms Millions live in each square meter of soil. Most are tiny and hard to see Cylindrical bodies Carnivores or herbivores Others are PARASITES! Have a digestive system like a tube, open at both ends. A one-way digestive system: food broken down; absorbed; wastes eliminated.

Ascaris – intestinal roundworms

Annelida – Segmented worms Earthworms Sea-floor worms Leeches

Annelids: Things in common Segmentation Live in almost all environments Most burrow or live in tubes “sit-and-wait” predators Closed circulatory system

Earthworms Eat dead or decaying things Skin needs to be moist to obtain oxygen Good for soil: Make it more fertile Loosen it Allow air, water, and plant roots to move through it

Worm dissection – what you should expect to see