ABSTRACT
In our continuing biological studies of echinoderms of the northern Gulf of Mexico, we have compiled some novel ecological observations of the paxillosid sand sea-star, Astropecten articulatus. We have examined individuals collected over time from two sites separated by a distance of approximately 28 km, and determined that each site has differing population characteristics with respect to (1) the size frequency distribution of R (arm length measured from the center of the body to the tip of the ray) and r (central body radius measured from the center of the body to the body margin between the intersection of two rays), and (2) the nature and incidence of sub-lethal arm loss in the two populations. Individuals at site A-1 and A-2 had mean R and r values of 53.9 and 11.4 mm and 38.4 and 8.3 mm. Mean sizes of R of individuals at site A-1 (N=652) were significantly (p<O.O1) larger than individuals at site A–2 (N=147). We also found significant differences (p<0.01) in numbers and frequency of arms regenerating by size class at both sites. In each population, the incidence of the number of arms per individual showing sub-lethal arm loss declined rapidly, with the greatest number of individuals having only one arm showing regeneration.
