Meeting Abstract
Planktotrophic marine larvae require exogenous nutrients in order to grow and develop. Typical sea urchin larval forms, or echinoplutei, exhibit eight arms. These ciliated arms allow for both feeding and swimming. The derived form of Centrostephanus coronatus (crowned urchin) larvae, however, only possess two long arms. This research seeks to understand the physiological consequences of such anatomical differences in larval forms through a detailed analysis of metabolic growth efficiency. We hypothesized that the dramatic difference in morphology of C. coronatus would result in significantly different growth efficiency relative to typical echinoplutei forms. Larvae were cultured under relatively high food concentrations (20,000 Rhodomonas sp. cells mL-1). Rates of larval feeding, growth, and metabolism were measured throughout development. Larvae ingested 81,263 algal cells ind-1 by day 37, resulting in the acquisition of 186 mJ of energy. Analysis of metabolism determined that larvae used a total of 34 mJ by day 37. Protein growth resulted in the deposition of 1,458 ng protein. This resulted in a gross energetic efficiency of 68%. Protein growth efficiency was determined to be 37% (protein ingested standardized to protein grown). These values will now be compared against the growth efficiency of more typical echinoplutei forms. This research will be important for addressing the role of morphological variation in determining the physiological and biochemical efficiency of larval growth and development and its role in larval dispersal.
