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Updated: Jul 19, 2026

Physiological Experimentation with the Crayfish Hindgut: A Student Laboratory Exercise
Published on: January 18, 2011
GABA and glutamate specifically induce contractions in the sponge Tethya wilhelma
Kornelia Ellwanger1, Andre Eich, Michael Nickel
1Department of Zoology, Biological Institute, University of Stuttgart, 70550, Stuttgart, Germany. michael.nickel@bio.uni-stuttgart.de
Abstract:
Sponges (Porifera) are nerve- and muscleless. Nevertheless, they react to external stimuli in a coordinated way, by body contraction, oscule closure or stopping pumping activity. The underlying mechanisms are still unknown, but evidence has been found for chemical messenger-based systems. We used the sponge Tethya wilhelma to test the effect of gamma-aminobutyric acid (GABA) and glutamate (L: -Glu) on its contraction behaviour. Minimal activating concentrations were found to be 0.5 microM (GABA) and 50 microM (L: -Glu), respectively. Taking maximum relative contraction speed and minimal relative projected body area as a measure of the sponge's response, a comparison of the dose-response curves indicated a higher sensitivity of the contractile tissue for GABA than for L: -Glu. The concentrations eliciting the same contractile response differ by about 100-fold more than the entire concentration range tested. In addition, desensitising effects and spasm-like reactions were observed. Presumably, a GABA/L: -Glu metabotropic receptor-based system is involved in the regulation of contraction in T. wilhelma. We discuss a coordination system for sponges based on hypothetical chemical messenger pathways.
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