Growth of crustacean muscle: Asymmetric development of the claw closer muscles in the lobster, Homarus americanus

Muscle fiber types were examined in lobsters using sarcomere length measurements. In the adult, the slender cutter claw was comprised of fast and slow fibers, while the broader crusher contained only slow fibers. In the juvenile lobster, both the cutter and crusher contained fast and slow fibers. Lengthening of sarcomeres is postulated for some fibers during growth and development of crustacean muscle.