Meeting Abstract
P1.6 Monday, Jan. 4 Respiration rates and energetic content of larvae of a tropical ophiuroid: comparisons with a with a sympatric echinoid. WHITEHILL, E.A.G.*; MCALISTER, J.S.; MORAN, A.L.; Clemson University; Clemson University; Clemson University whitehi@clemson.edu
Larvae of sea urchins and brittle stars are morphologically convergent, but it is not known if this morphological similarity is paralleled by similar developmental energetics. We reared larvae of the tropical brittle star Ophiocoma sp. (egg diameter = 71 µm) and a sympatric echinoid Echinometra vanbrunti (diam. = 68 μm) without food, measured oxygen consumption, and sampled larvae for biochemical content. Embryonic and larval metabolic rates of Ophiocoma ranged from 1.2 pmol O2 larva-1 h-1 at the gastrula stage to a high of 3.9 pmol O2 larva-1 h-1 at the 2-arm stage. After reaching the 2-arm stage, development stalled and larval metabolic rate fell to a range of 1.3 to 1.5 pmol O2 larva-1 h-1 for the next 4 days. To our knowledge, this is the first study of developmental energetics of ophiuroid larvae. The metabolic rates of Ophiocoma we measured are substantially lower than metabolic rates of E. vanbrunti, although the metabolic rates of the E. vanbrunti larvae showed the same general trend of increasing during morphogenesis and subsequently decreasing to a steady level at the 4-arm stage. Larval respiration rates of Ophiocoma also appear lower than echinoid larvae in general. We are currently examining changes in protein, lipid, and carbohydrate content of these larvae to compare larval energy budgets of Ophiocoma and Echinometra.
