Escape Reflexes in Earthworms and Other Annelids

Abstract

Escape or startle reflexes are characteristically seen in many representatives of the Phylum Annelida (segmented worms), a group that comprises the earthworms, aquatic oligochaetes, leeches, and marine bristle or polychaete worms. From the standpoint of defense, the escape reflex represents one of the most important components of a worm's repertoire of locomotory behavior that, depending on the species, may also include undulating swimming or peristaltic creeping movements. The underlying control and coordination for all of these locomotory movements are carried out by the worm's central nervous system, which consists of a dorsal brain in anterior segments and a ventral nerve cord, the latter being composed of a chain of segmentally arranged ganglia joined by longitudinal connectives.