Following damage, solitary fungiid corals are particularly successful in their ability to repair and regenerate their tissues and skeleton. When repair is impossible, these corals turn to budding as a mode of survival. The present study examines the hypothesis that when repair is not attainable, fungiid corals develop buds from tissue remnants in order to survive, and describes for the first time the mechanism of bud formation in 3 species of fungiids. Dead specimens of the fungiids Fungia scutaria, F. granulosa, and F. horrida collected from under 10 m belt transects from the coral reef in Eilat (Red Sea) were found to contain live buds of various sizes. Bud formation was experimentally induced to confirm the possibility that they may indeed arise from tissue remnants. The development of buds from tissue remnants on treated corals was detected after 4 to 12 mo. Tissue fragments removed from F. granulosa developed into planula-like balls, settled, attached, developed new mouths and consequently developed into new anthocauli. These results showed that small viable tissues fragments can reorganize and grow into whole new individuals. Twenty corals were broken into various sized wedge-shaped fragments which were cultured in the lab. Regardless of size, fragments containing no parental mouth tissues developed new mouths within 5 d and fully formed buds were visible 10 to 21 d after breakage. Coral fragments retaining part of the parental mouth regenerated tissues and skeleton around the original mouth but did not develop anthocauli. This suggests the presence of a morphogenetic factor inhibiting the development of additional mouths and thus of new buds in these specimens. The possibility of a trade-off between the processes of regeneration and bud development is discussed.
- Morphogenetic factor