ABSTRACT The seagrass ecosystems of the Tropical Northwestern Atlantic (TNA) host three described species of sea anemones in the genus Bunodeopsis Andres, 1881 (Enthemonae: Metridioidea: Acuticulata): B. antilliensis , B. globulifera , and B. pelagica . Due to their small size and nocturnal nature, many aspects of their basic biology and distribution remain unknown. To investigate their ecology and distribution, we surveyed five TNA ecoregions: Greater Antilles (Puerto Rico), Southern Caribbean (Curaçao), Southwestern Caribbean (Colombia and Panama), Western Caribbean (Belize and Mexico), and the Southern Gulf of Mexico (Mexico). Specimens were identified to genus, documented in situ and captively maintained for behavioral observations. Field methods combined nighttime snorkel observations and collection with macro and timelapse photography to document behavior, morphology, and asexual reproduction. We observed extensive morphological variation and presumably clonal aggregations in situ. Captive observations corroborated previously reported modes of asexual reproduction including pedal and vesicular scission, as well as revealed the previously unreported mode of transverse fission. Field observations revealed novel ecological interactions including predation on amphinomid polychaetes, association with the sacoglossan Elysia crispata , and predation by a reptantian ribbonworm (Nemertea: Reptantia). In Belize, standardized diurnal and nocturnal quadrat surveys at fixed distances from shore quantified Bunodeopsis spp. detectability, which was significantly greater at night regardless of observation depth. Nighttime detectability was approximately three times higher than during the day, supporting the conclusion that the lack of an abundance of reports of Bunodeopsis spp. is likely an artifact of underdetection than true rarity. The new occurrences reported here more than double previous records on GBIF, contributing resolution to the distribution of Bunodeopsis spp. Across five ecoregions in the TNA. These findings underscore the ecological importance of this genus of sea anemones in seagrass ecosystems and emphasize the need for surveys that target small, nocturnal, and understudied marine invertebrates.
PEN et al. (Sun,) studied this question.