Hopkins Marine Station Student Paper

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(full paper is archived in the Miller Library)

Title: "Giant" axon activity and excape behavior in the brittle star, Ophiopteris papillosa
Student Author(s): Burkhart, James
Faculty Advisor(s): Gilly, William
Pages: 23
Location: Final Papers Biology 175H
Date: June 1984
Keywords: movement
Abstract: The brittle star Ophiopteris papillosa exhibits an escape response to the predatory asteroid Pycnopodia. Stimulation of Ophiopteris with a tube foot of Pycnopodia evokes action potentials in the radial nerve chord (R.N.C.). Furthermore, recordings of these action potentials are similar both in velocity and amplitude to activity evoked by electrical stimuli of the R.N.C. itself. Also, the axons mediating these aciton potentials appear to be independent of external Ca++ ions and to run uninterupted by chemical synapses for at least several millimeters. These axons are probably transmitting sensory information, as tube foot stimulus is a sensory stimulation. In addition, the velocity of action potentials in these axons are about 17 times faster than propogation of the apparent motor output.