Fragmentation, re-attachment ability and growth rate of the Mediterranean black coral Antipathella subpinnata
Cnidarians are known for their simple body plan and their complex life cycles, involving high regenerative and asexual-reproduction potential. In particular, several asexual reproductive strategies are known for anthozoans, including fragmentation, carried out by tentacles, by groups of polyps or by portions of colonies. Here, we report the first observation of an extensive event of fragmentation in the Mediterranean black coral species Antipathella subpinnata (Antipatharia: Myriopathidae) in rearing conditions. Once detached, fragments lose their polarity and new anchorages are rapidly created with polyps and cnidocysts participating in the adhesion phases. Multiple attachments are frequently observed, with new skeletal plates produced through the expansion of spines. Dendritic spines gradually arise on these new plates. Fragments start to generate numerous new branchlets orientating upward and with a fixed arrangement. In 7 months of monitoring, fragments revealed fast growth rates, up to 1.85 and 1.58 cm month−1, for the whole fragments and new branchlets, respectively. Attachment of black coral fragments has never been recorded in the field; nevertheless, frequent adhesions observed in aquaria suggest that fragmentation could be a successful reproductive strategy in these anthozoans.
Authors would like to thank the two reviewers who significantly improved this manuscript with their helpful suggestions, the Carabinieri Military Force (Centro Carabinieri Subacquei di Genova in particular Marshal Duilio Lenzini’s team) and the diving center “Il Grande Blu” for their help during sampling procedures; Acquario di Genova Mediterranean Staff Department for the knowhow and support in black corals’ husbandry and the Scanning Electron Microscopy Laboratory of the Department of Earth, Environment and Life Sciences, University of Genoa. This work was funded by BIOMOUNT project MIUR-SIR (RBSI14HC9O, Biodiversity patterns of the Tyrrhenian Seamounts).
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Conflict of interest
The submitting author declares, on behalf of all the authors, no financial, personal or professional conflict of interests.
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