Meeting Abstract

P1-82   -   Examining the benefits versus costs of brooding in the brittle star, Amphipholis squamata McGrath, A/R*; McAlister, J/S; College of the Holy Cross; College of the Holy Cross armcgr22@g.holycross.edu

Brooding is a life history strategy found in some small marine invertebrates. Evolution has likely maintained brooding in these animals because the benefits of developing offspring internally likely outweigh the costs. The benefits versus costs of brooding have not been directly tested, however. This study aimed to investigate the benefits of brooding versus the costs of not brooding with respect to skeletal growth in juveniles of the brittle star, Amphipholis squamata. For this study, adult brittle stars were stained with calcein fluorescent dye to mark growth before the start of the experimental period; stained juveniles were then dissected from the bursal slits of mothers at different times during juvenile development. The dissected brittle stars were compared to juveniles that emerged, independently of researcher intervention, from stained mothers. Images were collected at each weekly sampling event of the adult mothers and all juveniles; juveniles that emerged during the experimental period were photographed the day they emerged. ImageJ analysis software was used to measure various parameters of growth, relative to the calcein mark, during the 28-day experimental period. Arm length, width, and quantity of skeletal vertebral ossicles per arm were measured and compared across experimental sampling timepoints. Data collection and statistical analyses are currently underway, and results will be presented with respect to published metrics of growth and arm regeneration for A. squamata and other brittle star species. The results of this study will provide insight into the evolutionary significance of brooded juvenile growth as a reproductive life history strategy that has been maintained in small marine invertebrates.