Effects of temperature on the body form, growth, electron transport system activity, and development rate of an echinopluteus

Abstract

The development rate from fertilization to the six-armed pluteus stage in Dendraster excentricus (Eschscholtz, 1829) was markedly temperature-dependent. It took three times as long to reach the six-armed stage at 12°C as it did at 22°C. The respiratory electron transport system (ETS) activity of six-armed plutei was also temperature-dependent between 12 and 22°C at a limiting substrate concentration. In spite of temperature-induced variation in development rate and metabolism, body size (length and protein content) and shape (ciliated band length and body symmetry) of the six-armed plutei did not vary with culture temperature. The sequence of form changes during larval development from the two-armed to the eight-armed stage were also independent of temperature (10–15°C). Plutei, given excess food, maintained the correspondence between growth rate and development rate. An important consequence of form constancy is the lack of change in ciliated band length with temperature. Band length determines larval feeding capability, defined as the maximal volume of water cleared of particles per unit time per larva. Since ETS activity is temperature-dependent, metabolic demand should increase with increasing temperature. It might be difficult for plutei (and other organisms that feed with the single band, upstream particle capture mechanism) to maintain energy balance under natural, food limiting conditions at high temperature. This could result in smaller larvae or modification of larval shape.