Morphology and Life Habits of the Recent Cementing Bivalve Spondylus Americanus Hermann from the Bermuda Platform

The morphology, ontogeny, distribution and life habits of the thorny oyster Spondylus americanus Hermann from the Bermuda Platform have been investigated, with a view to aiding paleoecological reconstructions in fossil relatives. The species is ubiquitous over a wide variety of environments throughout the Platform, but its distribution is primarily controlled by the availability of a suitably firm coral-encrusted substrate.

Five main modes of life of S. americanus occur: 1) cemented to the exposed, steep face of coral reef masses; 2) attached to the roof and walls of crevices and cavities in the reef, where it forms part of the cryptofauna; 3) cemented to the lee side of foliaceous corals, particularly Agaricia fragilis, where it is typically associated with an algal-foraminiferal-brachiopod-bryozoan cryptic assemblage; 4) within the abandoned concave valves of earlier-generation S. americanus in shell beds; 5) lying free in sediment pockets and sand channels, having been dislodged from its cemented habit by storms or predators.

The paradigmatic approach to functional morphology has been utilized to ascribe likely functions to the various spine types in S. americanus. Finally, the main taphonomic processes responsible for the reduction of the spondylid shell to skeletal detritus have been discussed and evaluated.