Mechanical resistance of reefbuilders through time.

Comparative studies on the mechanical properties of calcium carbonate skeletons suggest that reefbuilders adopted contrasting strategies through the ages to cope with hydrodynamic forces. From the superior mechanical strength of the coralline sponge Ceratoporella nicholsoni it is concluded that its forebears, the stromatoporoids, built a very resistant framework in Paleozoic/Mesozoic reefs. Scleractinians and other modern reefbuilders, however, are comparatively fragile. They compensate breakage and wear by rapid growth due to zooxanthellae-enhanced calcification.