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Echinodermata

Echinodermata. Alyssa Price and Katy Fanning Period 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

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Echinodermata

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  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

  7. 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)

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

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