Top 10 New Species 2008! Top Ten

Phylum Platyhelminthes

Biology 11

General Characteristics About 20 000 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)