In Greek Arthropoda means “jointed legs” All Arthropods have 4 common characteristics: Exoskeleton Segmented body “open” circulatory system Jointed legs …. But why do they need jointed legs? Phylum Arthropoda

Arthropods have an “outer” skeleton called an Exoskeleton. How do arthropods grow bigger, if their skeleton is on the outside of their body?

Planaria Feeding

What are Planaria? Freshwater flatworms (phylum: Platyhelminthes) Live in freshwater under leaves and stones Avoid light (“negative phototaxis”) Free living – not parasites Carnivores – eat decaying meat, insects and larvae (egg yolks or liver in the lab) 1-20 mm in size Long lived Use sexual or asexual reproduction This picture has been released it into the public domain.

Overview of Brown Planaria Dugesia tigrina

Planaria are complex organisms Gastrovascular System