THE CHEMICAL COMPOSITION AND MECHANICAL PROPERTIES OF THE HINGE LIGAMENT IN BIVALVE MOLLUSCS

1. The bivalve ligament protein has a high percentage of glycine.2. The absence of hydroxyproline and hydroxylysine in the ligament and the lack of a wide angle diffraction pattern indicate that the ligament is not collagen.3. The ligament contains more sulfur amino acids—methionine and cystine/2— than other structural proteins.4. Only the aragonite phase of calcium carbonate has been observed in association with the ligaments.5. Members of the family Pectinidae have the weakest and most resilient ligaments.6. Resilience is inversely correlated with CaCO3 and cystine/2 concentration while glycine is directly correlated with resilience.7. The strength factor (opening moment/gram of shell) is distinct from resilience and does not correlate with any of the parameters examined.8. Recovery from compression by inner ligament is probably mediated through easing of steric strains induced during compression.