Mucus as a mediator of gametogenic synchrony in the sea cucumber Cucumariafrondosa (Holothuroidea : Echinodermata)

The data presented here demonstrate that the sea cucumber Cucumaria frondos a secretes a biologically active mucus that helps maintain gametogenic sync hrony among conspecifics. Either a whole mature individual or a sample of i ts freshly collected mucus was able to initiate gametogenesis in conspecifi cs that were in the gametogenic recovery stage when other environmental con ditions, including daylength, were maintained constant. Similar results wer e obtained when thr mucus was kept in seawater for less than 3 h prior to i ts use, whereas after Gh in seawater; the mucus had lost its inducing prope rties. Laboratory experiments showed that the mucus was produced in lesser amount during late summer and autumn; the production rapidly increased in e arly January to reach a peak a few months before the June spawning, in 1992 and 1993. The increment of mucus production was concurrent with the initia tion of gametogenesis. Synthesis of mucus was maximal in individuals having attained gametogenic maturity and minimum in individuals with less develop ed gonads. At first relatively stable in seawater, the mucus gradually lost its integrity within a period of 3-5h, suggesting that the mucus may be ca rried over long distances by currents, thus allowing a transfer of informat ion before its complete degradation. This phenomenon was observed in the fi eld where screams of mucus could bt: followed by SCUBA divers as far as 20- 30 m away from the secreting animal. The data presented here are the first evidence of the important role played by mucus secretion during the gametog enic processes of an echinoderm.