Ligament (bivalve)

The lamellar layer consists entirely of organic material (a protein and collagen matrix), is generally brown in color, and is elastic in response to both compressional and tensional stresses.

The fibrous layer is made of aragonite fibers and organic material, is lighter in color and often iridescent, and is elastic only under compressional stress.

[3] A recent study using scanning electron microscopy(SEM), X-ray diffraction (XRD), and infrared spectroscopy (FTIR), found that some bivalve mollusks have a third type of fibrous layer in the ligament (located in the middle) which has a unique spring-like protein fiber (ca.

Scallops (Pectinidae) swim through the water column by rapidly and repeatedly clapping (opening and closing) their valves.

An interesting fact about scallops swimming in this manner is that they recover a greater percentage of the work (as defined by physics) performed through the elasticity of their abductin than do other bivalves (which are more sedentary clams).

The taxonomic distribution of ligament types among families of bivalves has been used by paleontologists and malacologists as a means of inferring phylogenic evolution.

[6] An internal ligament is usually called a resilium and is attached to a resilifer or chrondophore, which is a depression or pit inside the shell near the umbo.

J. G. Carter, Evolutionary significance of shell microstructure in the Paleotaxodonta, Pteriomorphia and Isofilibranchia (Bivalvia: Mollusca).