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Biol Bull 157: 189-204. (August 1979)
© 1979 Marine Biological Laboratory
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EVOKED RESPONSES TO ELECTRICAL STIMULATION IN THE COLONIAL HYDROID CLAVA SQUAMATA: A CONTRACTION PULSE SYSTEM

DARRELL. R. STOKES 1 and NORMAN B. RUSHFORTH 1

1 Department of Biology, Emory University, Atlanta, Georgia 30322; Department of Biology, Case Western Reserve University, Cleveland, Ohio 44106; and The Marine Biological Laboratory, Woods Hole, Massachusetts 02543

1. At least two conducting systems are present in the colonial hydroid, Clava squamata, the contraction pulse system (CP system) which initiates symmetrical polyp contraction, and a delayed burst system (DBS) which is correlated with tentacle depression and polyp contraction.

2. The CP system has properties similar to contraction pulse systems of other hydroids; its electrical pulses are of large amplitude (greater than 0.5 mV) and long duration (150 msec), and slow conduction velocity (2-3 cm/sec).

3. The CP system courses through the polyps and their interconnecting stolons. Electrical stimulation of a single polyp gives rise to CPs associated with contraction of that polyp, which sometimes can be recorded also in adjacent polyps.

4. Isosmotic MgCl2 abolishes CPs and associated column contractions, but does not suppress delayed burst pulses.

5. Light initiates contractions of the polyp and correlated CPs.

6. It is postulated that the CP system of Clava is similar to contraction pulse systems previously described for other hydroids.






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Copyright © 1979 by the Marine Biological Laboratory.