ABSTRACT
The sand dollar Dendraster excentricus of the North American west coast is famous for its vertical feeding posture. I know of no other report of this posture for any other sand dollar. A population of Encope michelini L. Agassiz on the Florida gulf-coast shelf (27° 32.4 N, 82° 29.1 W, 18 m depth) shows both horizontal and vertical postures. The vertical posture of individuals was observed on two occasions. On the first (7 Sept 2002), the vertical posture of a large proportion of individuals was noted at dusk. On the second (2 July 2003) the population was observed before and at dusk. All individuals had the horizontal posture before dusk. At dusk 54% of the individuals had assumed the vertical posture. This suggests the vertical posture is nocturnal and controlled by light, probably in response to diurnal predation. The posterior test edge of some individuals showed evidence of damage indicative of sub-lethal predation. Encope michelini does not show conspicuous anterior displacement of the mouth and apical system as seen in Dendraster excentricus.
