Crayfish muscle fiber: spike electrogenesis in fibers with long sarcomeres.

Most of the muscle fibers in the walking legs of the crayfish Procambarus clarkii generate only graded electrical responses. However, some fibers in extensor muscles of the carpopodite have long sarcomeres, about 10 micrometers in length, and generate overshooting spikes that have conduction velocities of 0.3 meter per second. The spikes induce twitch contractions.