Biochemical and energetic composition of bathyal echinoids and an asteroid, holothuroid and crinoid from the Bahamas

Abstract

The biochemical and energetic composition of body components of ten species of bathyal echinoids, and an asteroid, a holothuroid and a stalked crinoid were determined from individuals sampled from a variety of deep-water sites near the Bahamas (north Caribbean Sea) in October 1988. When compared with other studies of echinoderms, no geographic- or depth-related differences in biochemical or energetic composition were found. Body-wall tissues were composed primarily of skeletal material (mineral ash), but were comparatively high in organic material in the echinothuriid echinoids, and the asteroid and holothuroid. Gut tissues and pyloric cecae had high levels of lipid and protein, indicating their potential role in nutrient storage. Body-wall tissues were generally low in energy, but were highest in the echinoidsAraeosoma belli (7.7 kJ g−1 dry wt) andSperosoma antillense (8.0 kJ g−1 dry wt), the asteroidOphidiaster alexandri (8.9 kJ g−1 dry wt), and the holothuroidEostichopus regalis (13.1 kJ g−1 dry wt). Energy levels of gut and pyloric cecal tissues were two to three times higher than those of body-wall tissues. Total somatic tissue energy values varied greatly among species, ranging from 1.5 kJ in the echinoidAspidodiadema jacobyi to 142.1 kJ inE. regalis. As the bathyal echinoderms examined in this study occur in great abundance, they represent a significant reservoir of organic and inorganic materials and energy in deep-water benthic systems.