Self‐organization and emergent individuality of favositid corals adapted to live on soft substrates

Seilacher, A. & Thomas, R.D.K. 2011: Self‐organization and emergent individuality of favositid corals adapted to live on soft substrates. Lethaia, Vol. 45, pp. 2–13. Secondary soft‐bottom dwellers share the problem that their ancestors, attached to hard substrates, had lost their mobility. On soft substrates, only a limited number of alternative tricks are available to maintain sessile organisms in life position or to right them following disturbance. Consequently, convergent adaptations have emerged in unrelated members of this ecological guild. Those of favositid corals are of particular interest because, on account of their small polyps, they were always colonial. A comparative analysis of forms adopted by favositids on soft substrates shows that key elements of their adaptive paradigms could have been achieved by self‐organization. This arose without centralized control by means of inherited reaction norms of individual polyps to local environmental conditions. The unique spiral growth habit of Favosites turbinatus Billings and its emergent individuality at the colony‐level of organization are explained in these terms. ‘Suicidal’ lids entombed altruistic marginal polyps, forming a secondary epitheca as the growing colony settled into the sediment. These lids also record the size and spacing of soft tentacles in this species. □Coloniality, Devonian, Favositida, Favosites turbinatus, morphogenesis, self‐organization, Tabulata.