Unformatted text preview: Phylum Annelida & Arthropoda (i.e Earthworms and insects) a) Simply contain more nerve cells b) Have ganglia and ventral nerve cords (clusters of neurons that are arranged in) 5) Phylum Chordata (i.e Vertebrates) a) Consist of a brain and ventral longitudinal nerve cords b) Cerebrospinal Fluid = The blood-derived fluid that surrounds the brain Main components = Glucose, high concentrations of sodium, chloride, and calcium ions, and low concentration of potassium ions. Main functions = to protect against infection (immunity) = to nourish and cushion the brain and spinal cord Significance = the composition of sea water is similar to this and the organisms might have come from the water and this provides enough nutrients to the humans....
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- Fall '11
- ventral nerve cords, longitudinal nerve cords