Marine & Environmental Sciences Faculty Articles





Document Type


Publication Title

Marine Biology



Publication Date



marine biological invasion, alien Ophiothela, octocoral hosts, Coeloplana, Caprella predation, subtropical Florida, behavioral effects


Widespread and large populations of the exotic eastern Pacific ophiuroid brittle star Opthiothela mirabilis now occur in southeastern Florida, extending the range of this recently introduced species from southern Brazil northward to the eastern Caribbean Sea and Florida. The Florida brittle stars, representing two lineages, are epibionts on shallow (3-18 m depth), tropical/subtropical plexaurid (e.g., Eunicea spp., Muricea elongata) and gorgoniid (Antillogorgia spp.) octocorals. The scope of this study includes recent distributional records of O. mirabilis in south Florida, field abundances in relation to the cohabiting endemic ctenophore Coeloplana waltoni, behavioral observations of the ophiuroid, ctenophore and the predatory amphipod Caprella penantis, as well as a laboratory experiment testing the effects of the alien ophiuroid on the native ctenophore. Individuals of O. mirabilis have been collected near St. Lucie Inlet, extending its northern-most range by about 110 km since 2019. Two years of field sampling have demonstrated significant declines of the native, benthic ctenophore with increasing abundances of the exotic ophiuroid. Evidence suggests that the ophiuroid is negatively affecting the abundances of the ctenophore through interference competition, greatly aided by its abrasive armature of calcareous spines, plates and hooks. Sporadic and intense predation by a caprellid amphipod (Caprella penantis) also probably contributes to the ctenophore’s decline, but to a lesser extent than that caused by the ophiuroid. Adding to the risk of extinction of C. waltoni is its narrow requirement of living octocorals as hosts and restricted distribution in southeast Florida and the Bahamas.



First Page


Last Page



Thanks are due W. L. Bullock (Landis), B. Enright, R. L. Ionata, and the South Florida Beach Divers Meetup Group for help with obtaining collections, and to Markus Niemeyer for the report and specific location data on O. mirabilis at Blue Heron Bridge. A special thanks to Julie Gross for sundry laboratory tasks and enlightening discussions. R. C. Brusca, D. Cadien, D. Drumm, and Lea-Anne Henry offered literature sources, helpful discussions, and contacts with systematists for species identifications. J. M. Guerra-García kindly identified Caprella penantis. and Dale R. Calder a hydrozoan. We are grateful for details on the Bunaken caprellid infestations provided by Carlo Cerrano. The Ophiothela collection at Blue Heron Bridge was under FWC Special Activity License SAL-20-2267-SR.

Additional Comments

This work is licensed under a CC BY 4.0 License

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Peer Reviewed