Abductin is one of the five rubber-like solids used by animals to provide elasticity in biological systems; the others are elastin, resilin, spider silk, and ColP.
Abductin appears exclusively in the hinge ligament of bivalve mollusks, and the name comes directly from its function: abductin ligaments oppose the adductor muscles that open and close the valves (shell halves) of the Bivalvia. When the shells close the abductin is compressed; when the adductor muscle relaxes the energy stored in the abductin pops the valves apart. Incidentally, abductin is the only biological elastomeric protein designed to work primarily under compression, rather than tension.
Abductin shows a fairly wide range of efficiency, with the most effective energy storage being found in the abductin of swimming bivalves; some bivalves, most particularly the scallops (Pectinidae) swim by rapidly opening and closing their valves, up to
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