Date of Award


Document Type


Degree Name

Master of Arts




Chrysaora quinquecirrha nematocysts and isolated in suspension were systematically exposed to a wide range of chemical and mechanical stimuli to determine which ones would initiate discharge.

Nematocysts in situ were found to be highly responsive to stimuli and showed well-marked, immediate discharge when treated with acid, base and electrical stimuli. Slight discharge occurred with salt solutions, beef extract, beef extract and contact, human hair and change in temperature.

Discharge increased with the concentration of the reagent or the strength of the mechanical stimuli. A significant increase in discharge occurred in isolated nematocysts treated with HCl, acetic acid and sodium hydroxide. The amount of discharge was found to increase with time.

In comparing nematocysts to isolated ones it was found that the former show a greater sensitivity to stimuli. They respond to a larger number of stimuli,

they respond faster and at lower concentrations than do isolated nematocysts. This difference seems to indicate that the presence of the cnido blast is essential for immediate discharge and that a cellular process is involved.

In si tu nematocyst discharge in response to food or contact appears to involve a two-fold stimulus, chemical and mechanical, as has been suggested by other investigators.

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