Nutrient and energy allocation during arm regeneration in Echinaster paucispinus (Clark) (Echinodermata; Asteroidea)

Abstract

Individuals of Echinaster paucispinus (Clark) were either intact or had two arms amputated, and fed a sub-maintenance ration of food. After 7 months, the new arm was 17% the radius of the intact arm. This rate of regeneration is much lower than that of other species of asteroids fed similar food levels. The greater amount of protein in the body wall of Echinaster paucispinus may be responsible. Gonadal growth occurred in both intact and regenerating individuals with an overall decrease in size of the pyloric caeca. Allocation to reproduction takes precedence over the deposition and retention of nutrient stores. Regenerating individuals gained energy (kJ), while intact individuals lost energy. This difference may result from a combination of higher food levels/individual and more efficient food utilization and decreased maintenance requirements (especially of body wall). This leads to more energy available for growth. Asteroids in general, show similar responses in allocation to the disturbance of arm loss and the stress of sub-optimal food. The stress-tolerant species, Echinaster paucispinus, has a slow rate of arm regeneration.