Polyp Bail-out Research Articles

Polyp bail-out by the coral Astroides calycularis (Scleractinia, Dendrophylliidae)

Knowledge of reproductive biology is essential for ecological studies on coral population dynamics. The azooxanthellate colonial coral Astroides calycularis is endemic to the western Mediterranean Sea and adjacent Atlantic coasts. Specimens of this species in artificial conditions, an aquarium with enclosed seawater and low food availability, appeared to show an asexual dispersal mechanism. This mechanism consisted of the detachment and release of single, skeletonless polyps from the underlying colony skeleton (i.e., polyp bail-out). While the released free-living polyps regularly showed extended tentacles and most of them survived, they did not show re-attachment to the substrate or any skeleton formation until the end of the experiment, ∼2–3 months after bail-out. Formation of new reproductive colonies, thereby the eventual completion of asexual reproduction through polyp bail-out in A. calycularis, still needs to be confirmed. In addition to sexual reproduction, polyp bail-out may constitute an alternative propagation mechanism during periods of environmental stress, thereby potentially increasing the survival rate of the parental genotype and the dispersal by drifting soft polyps.

Response to higher sediment loads by Pocillopora damicornis planulae

Planulae collected from the reef coral Pocillopora damicornis were exposed to four different levels of sediment (0, 10, 100, 1000 mg l-1) for 14 days under two contrasting water agitation levels (aerated vs. non-aerated). There was no significant difference in larval settlement among the varius sediment treatments and between agitation levels used in this study. However, a significant number of settled planulae underwent reversed metamorphosis (“polyp bail-out”) in the 100 and 1000 mg l-1 treatments of both water aeration regimes indicating conditions were not appropriate for continued development and growth. Data suggested that successful recruitment may be limited in areas with greater than normal sediment loads.

Polyp Bail-Out: An Escape Response to Environmental Stress and a New Means of Reproduction in Corals

Polyp Bail-Out: An Escape Response to Environmental Stress and a New Means of Reproduction in Corals