Top 10 New Species 2008!  Top Ten Top Ten

Phylum Platyhelminthes Biology 11

General Characteristics  About species  Simplest animals with bilateral symmetry  Can move forward in certain direction  Have organs and organ systems

3 Classes  Flukes: class trematoda  Tapeworms: class cestoda  Free Living Flatworms: class turbellaria

Planaria - Adaptations  Eyespots  Flat shape, places all cells close to surrounding water  Highly branched GVC (gastrovascular cavity)

Planaria - Response  Ganglia  Head with eyespots  Lateral flaps - function for smell  Avoid light

Planaria - Nutrition  Carnivores that prey on smaller or dead animals  Mouth extends from medial ventral side with an external pharynx  Prey digested by enzymes in GVC (extracellular digestion)  Food absorbed by cells in branches of GVC  Waste released out through mouth

Planaria - Locomotion  Move using cilia on ventral epidermis  Glide along mucus that they secrete  Some flop using muscles

Planaria - Reproduction  Asexual regeneration  Sexual hermaphrodites (but no self fertilization)