Fission, regeneration, gonad production and lipids storage in the pyloric caeca of the sea star Allostichaster capensis

Allostichaster capensis is a fissiparous sea star that displays an annual sexual and asexual reproductive cycle. After fission, individuals spend the rest of the year regenerating the missing arms. To analyze feeding rates, we conducted three experiments with sea stars in different states of regeneration: recently split, regenerating and arms with advanced regeneration. Three different treatments of food availability (high, intermediate and low) were carried out during each experiment. We found that food availability and regeneration state had an important effect on feeding rates. Recently split individuals showed the lowest values of feeding rates, amount of lipids in the pyloric caeca and gonad production, regardless of the food treatment. Regenerating individuals had the highest feeding rates, allocated of resources in the pyloric caeca and produced gametes. Individuals with arms in an advanced regeneration state showed intermediate feeding rates and no deposition of lipids in the pyloric caeca. These individuals spawned during the experiment, thus indicating that the gonads were mature. Low food availability produced the lowest feeding rates regardless of the regeneration state. Regenerating individuals died only in low food availability. No death was observed in individuals with advance regenerated arms. On the other hand, individuals that had recently undergone fission died regardless of the food availability. Since fission and regeneration are part of the life-history of A. capensis, regenerating individuals may have high feeding rates to achieve a good nutritional state to support regeneration, gamete production and survival after fission.