Mutualism Among Sessile Invertebrates: A Mediator of Competition and Predation

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Science  20 Feb 1981:
Vol. 211, Issue 4484, pp. 846-848
DOI: 10.1126/science.211.4484.846


Hydroids of the genus Zanclea are epizoic on encrusting bryozoans. The bryozoans protect these hydroids with skeletal material. Zanclea polyps on the bryozoan Celleporaria brunnea sting small predators and adjacent competitors, helping Celleporaria to survive and to grow over competing species. This mutualism enables the two species to cover a larger area than they could individually.