Mar 24, 2015
Domain: Eukarya
Group: Lophotrochozoans
Phylum: Platyhelminthes (Flatworms)
Class: Turbellaria
Planaria is a triploblastic, free-living flatworm that lives in freshwater ponds. The two ocelli (eye-like structures) consist of pigmented cups lined by sensory cells. The cup shades the sensory cells from light in all directions except one which results in planarians exhibiting negative phototaxis (meaning they move away from light). The Planaria may exhibit a pair of auricles or ear like projections at the base of the head, which are sensitive to touch and the presence of certain chemicals.
Photograph from:www.weinberg.northwestern.edu