Retractile Polyps of Soft Coral Gersemia rubiformis (Octocorallia: Alcyoniidae) Offer Protection to Developing Basket Stars (Gorgonocephalus sp.)

Cold-water soft corals are a known habitat for juvenile basket stars (Gorgonocephalus sp.), but the role of this relationship in the earliest life stages of basket stars warrants further investigation. Here, basket stars and colonies of the soft coral Gersemia rubiformis were collected together from the Funk Island Deep Marine Refuge (NW Atlantic) and maintained in a laboratory setting for observation. During this time, two developing (<1 mm disc diameter) basket stars were discovered on coral colonies and could be seen retracting with the coral polyp into the colony. The basket stars were recorded unharmed once the polyps were expanded again and continued to retract within the colony over the period of observation. The results of this study show that developing basket stars can spend time inside the coral colony, which could be a form of protection.