LOCOMOTION OF THE HOLOTHURIAN<i>EUAPTA LAPPA</i>AND REDEFINITION OF PERISTALSIS

Abstract

1. The apodous holothurian, Euapta lappa, demonstrates four types of peristalsis. Direct overlapping peristalsis in which circular and longitudinal muscle components overlap is the most common. Other types are characterized by (a) being of longitudinal muscles only, (b) lack of circular muscle contraction along one side of the body and (c) being of circular muscles only (nonlocomotory).2. "Warts" in apodous holothurians are not discrete structures but are areas of the body wall delimited by temporary contraction of circular muscles.3. Peristalsis is defined as any muscular contraction moving along a radially flexible tube such that each component wave of circular, longitudinal or oblique muscle contraction is preceded or followed by a period of relative relaxation of all similarly oriented muscle. Definitions and nomenclature are given for 8 locomotory and 4 non-locomotory types of peristalsis.