Abstract
A field study was undertaken on the cross-shore distribution and population structure of the sea cucumber Patinapta ooplax (Synaptidae) inhabiting an intertidal sand flat in Awaji, Hyogo Prefecture, western Japan. Two transects of six or seven sampling points each were sampled at two- to three-month intervals from May, 2008 to February, 2009. The sea cucumber inhabited a zone between mean tidal level and mean low water of spring tide, irrespective of season. The gonad index showed a higher value in summer than in other seasons. Autotomized individuals occurred throughout the year, being most abundant in late autumn. Mean body size was smaller in autumn than in other seasons.
