The Effect of Vitamins on Weight Gain and Organ Production in the Sea Urchin, Lytechinus variegatus (Echinodermata: Echinoidea)

We investigated the requirements for a commercial vitamin premix in diets of Lytechinus variegatus . Small L. variegatus (ca. 28 mm diameter) were collected from Saint Joseph Bay, Florida, and acclimated to laboratory conditions (32 ppt salinity, 22 C, 12:12 photoperiod) for 3 wk, then placed individually into plastic mesh cages ( n = 16 per treatment). Sixteen urchins were dissected to obtain initial weights of organs (gut, gonad, test). Each treatment was fed one of five semipurified diets supplemented with levels of a commercial shrimp vitamin premix ranging from 0 to 0.9% dry weight. At 4‐wk intervals, wet weights and test diameters were measured. At 16 wk, urchins were dissected and organs weighed. Significant weight gain and 100% survival was observed with all diets. At 16 wk, urchins fed 0% vitamin premix exhibited no noticeable pathology but had significantly less weight gain than those fed the 0.6% vitamin premix. Those fed the 0.6% vitamin premix had significantly greater weight gain than all other diets ( P < 0.0001). Gonad weights increased in all treatments, but did not vary significantly. Under the conditions of this study, L. variegatus exhibited a satisfactory nutritional response. Experiments are planned to determine specific dietary vitamin requirements for L. variegatus .