Diurnal rhythms and light regulated behaviour in the demosponge Tethya wilhelma

Activity: Talk or presentation typesLecture and oral contribution


5 minute speed talk given at the 11th World Sponge Conference.

Keywords: porifera, pre-nervous system, light reception, contractions, IR time-lapse

Even though sponges lack a nervous system, they are still able to perform coordinated behaviours, such as the whole-body contractions documented, among others, in the demosponge Tethya wilhelma. Also, a diurnal rhythm in the number of body contractions in this species has been indicated in previous studies. In this study, we investigated the role of light, and possible diurnal patterns in the contraction-expansion behaviour of T. wilhelma. The sponges were subjected to three different light regimes: 1) a simulated natural night/day-cycle with sunset and sunrise; 2) constant darkness; and 3) constant light. Our results showed that the behaviour of the sponge varies under different light regimes, and that a diurnal rhythm was present under a simulated night/day-cycle, that dissappeared under both constant light and constant dark conditions. We also demontrated a clear pattern with a contraction around sunrise under the night/day-cycle. This indicates the presence of exogenous regulation by ambient light, and therefore implicates light-sensing capabilities in this sponge species. The mechanism of the regulation of this behaviour, including the possible influence of microbial symbionts remains to be tested, but our study serves as a clear example of the complexity of sponge behaviour.
Period13 Oct 2022
Event title11th World Sponge Conference: Reconnected
Event typeConference
LocationLeiden, NetherlandsShow on map
Degree of RecognitionInternational