1. Echinodermata Alyssa Price and Katy Fanning Period 2

2. Symmetry Echinodermata evolved from animals with bilateral symmetry Pentaradial symmetry- arms radiate from the central body (pentamerous), each dividing into five equal segments Starfish have no heart, brain, or eyes Each arm has its own set of organs

3. Germ Layers Echinodermata have three germ layers: the ectoderm (outer), endoderm (inner), and mesoderm (middle). Do not have an external skeleton, but rather have a thin skin layer composed of calcified plates and spines The coelom is the secondary body cavity formed by the division of three body cavities The coelom is composed of two parts (the perivisceral coelom and the hydrocoel) Perivisceral coelom contains a watery coelom and the hydrocoel forms the water vascular system.

4. Movement Most Echinodermata are motile Their movement is controlled by nerve branches in the arms Some use water to hold them up and float in shallow areas Echinodermata use their water vascular system to move

5. Reproduction Females discharge their eggs into the water; Males discharge their sperm Gametes float in water until egg and sperm find each other in water (flagellated sperm) Females can produce 100 million eggs at once All echinodermata can regenerate new parts asexually

6. Life Cycle

8. Terms Tube feet- function of locomotion and feeding; the two muscles are ampulla and podia: the ampulla are the circular and longitudinal muscles and the podia are the latter muscles Spines- make up the outermost skin layer for the function of support Pentaradial symmetry- five equal parts around a central axis (usually the mouth) Water vascular system- network of canals that function in gas exchange, feeding and locomotion Two stomachs (starfish)- one is used for digestion and the other is used to engulf prey 5 classes- Echinoidea (sea urchins and sand dollar), Crinoidea (sea lilies), Asteroidea (starfishes), Ophiuroidea (brittle stars), Holothuroidea (sea cucumbers)

9. Videos http://www.youtube.com/watch?v=A100m5EpfFI http://www.youtube.com/watch?v=irERi_1OxmE http://www.youtube.com/watch?v=4IRF-pKVtuU