Repair scars on mactra violacea from the eastern coast of india: A new classification and a model for describing shell breakage on bivalves

Abstract

Non-lethal shell damage, which is preserved as repair scars on the bivalve shell, can be predatory or non-predatory in origin. When the peeling crabs are the main predatory groups, non-predatory damages are produced by impact from the saltating clasts or by wear and tear during burrowing. In both cases, these repair scars almost look alike, and it is difficult to identify which factor is causally responsible. Because survival of an individual is related to the severity of the shell-break irrespective of the cause, here, we have developed a classificatory scheme to categorize the repaired traces on the basis of intensity of the damage. Moreover, we have provided a model to analyze how the severity of scars can be effectively used to study species’ adaptation against shell breaking causes, by using Mactra violacea as a studied species. Individuals who survive shell breakage may adapt to escalated morphological traits to resist damage in the long term.