Hydrodynamic Self-Righting in Manicina Areolata, A Strategy with Palaeoecolgical Significance
10th International Coral Reef Symposium, Okinawa, Japan, June 28-July 2, 2004
The scleractinian Manicina areolata is a common coral on Caribbean hard and soft substrata and was studied at Lee Stocking Island (Exuma Cays, Bahamas). It is not only found on reefs but also on bioclastic sand with seagrasses. Investigated corolla ranged in size from 2 to 10 cm, growth form varied from conical with round to oval cross-section to turbinate forms with few meanders and flat oval cross-section. The conical morphotype was usually attached to hard substratum, while the turbinate morphotype was usually unattached and upright, in soft substratum. In infratidal areas, both attached and unattached turbinate forms were found in close vicinity, however, conical attached forms were rare. Habitats with sandy softgrounds, where free-living turbinate morphotypes were common, were influenced by strong tidal currents with concurrent danger of burial or “disorientation” of the corolla. Investigations in the flume channel showed that the colony shape itself led to passive cleaning and self-righting, which was achieved by the flat-turbinate morphology, with a concave side and a flat to slightly convex opposite side, under high current speeds. The concave side, and particularly the median lobes formed by many meandroid coralla, were the critical morphological factors. Grooves formed in between the lobes channeled currents in a way that scour underneath the coral and drag produced by the lobes allowed passive self-righting. This could be used to explain ecological strategies in similar-shaped fossil solitary corals.
Piller, Werner; Hubmann, B.; and Riegl, Bernhard, "Hydrodynamic Self-Righting in Manicina Areolata, A Strategy with Palaeoecolgical Significance" (2000). Oceanography Faculty Proceedings, Presentations, Speeches, Lectures. 93.