Tentaculate ctenophores, such as Pleurobrachia pileus, utilise a strong, fast-acting adhesive for prey capture. The adhesive is stored safely along their two branched tentacles in specialised cells called colloblasts. When prey contacts a tentacle, the adhesive is released and binds the prey. This mechanism of release and other basic questions about the adhesive are yet to be answered. To better understand the mechanisms controlling adhesive release, live video microscopy was applied to visualise adhesive release in response to probing. Probes of various surface chemistries were compressed into tentacle fragments and slowly withdrawn to see individual adhesion events. We found that compression was a requirement to stimulate consistent adhesive release, and that the larger the area compressed the more colloblast cells released adhesive. However, the proportion of colloblasts releasing adhesive was low. This finding suggests colloblast discharge may be a stochastic event, with a low baseline probability of activation. However, the exact mechanism underpinning colloblast discharge is unknown. To better understand the intracellular mechanisms governing adhesive release, exogenous perfusion of tentacle fragments with artificial sea water (ASW) was visualised under video microscopy. ASW of the same tonicity but containing higher proportions of calcium or potassium resulted in the formation of large vesicles along the surface of the tentacles, indicating adhesive release. High levels of magnesium or sodium resulted in relaxation of the tentacles, with no formation of these vesicles. These results indicate ionic regulation of adhesive release from colloblasts, and combined with other studies of colloblast origin, add weight to a potential neuronal origin of colloblast cells.