Differences between colonial and solitary corals

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In colonial corals, isografts invariably fuse, while, in solitary corals, isogeneic individuals do not fuse when they are brought into contact. Although the differences between colonial and solitary modes are ecologically important, few researches have been conducted on the mechanisms that cause physiological and morphological differences between solitary and colonial corals. The present study aimed to elucidate the mechanisms that produce the differences between solitary and colonial corals.To investigate whether solitary corals show colonial characters at early stages of development, we observed morphogenetic patterns of young polyps regenerated from tissue fragments of solitary corals Fungia spp. and did contact experiments using clonal polyps regenerated from tissues of the same individuals. When more than two polyps were regenerated from a tissue fragment, they remained as colonial form for 5-13 months observation period. When regenerated polyps derived from the same individual we … More re brought into contact, they fused. In one case, fusion occurred at stalk but not at disc. Some colonial forms separated into individual polyps while others changed to solitary form by integration, that is, fusion of tentacular rings and mouths. The present results suggest that solitary corals like Fungia showed colonial characters at early stages of regeneration. It has been suggested that Fungia acquire solitary characters when they from discs.Colonies of Pocillopora damicornis derived from primary polyps (settled planulae) and those regenerated from branch tips of adult colonies assumed different growth forms. Young colonies derived from primary polyps formed at least one branch from the central region of a colony, while colonies regenerated from adult branch tips(3-5 mm long) never formed branches during the nine months observation period. The results suggest that the rate of branch origination of P.damicornis colonies decreases with age. This Finding may open the way to analyze the mechanism of branch formation in corals at molecular level.We attempted to distinguish clones of a coral Pocillopora damicornis using histocompatibility assay and molecular markers. We found that microsatelite markers PV5 and PV7 were polymorphic to some extent but failed to detect genetic differences between siblings or between parent and offspring. We found that ITS1 sequences are highly variable in P.damicornis and pan be applied to studies on clonal structure within populations of the coral. Less