Non-Catch Contraction in Paramyosin-Containing Muscle in an Echinothuriid Sea Urchin Asthenosoma Ijimai

Abstract

It has long been known that certain molluscan smooth muscles become stretch resistant and can hold the shell closed for extended periods without fatigue and at low rates of oxygen consumption. This prolonged state of contraction is called catch, and the maintenance of catch force is at least 10 times more economical than the contraction that precedes catch. This mechanism has been extensively studied in the anterior byssus retractor muscle (ABRM) of Mytilus edulis (Rüegg, 1971, 1986).