Research Training Program

Smithsonian Institution
National Museum of Natural History

PROJECT SUMMARY
1997

Noah R Feinstein
Harvard University
Cambridge, Massachusetts
Stephen D. Cairns, Ph.D.
Supervising Scientist
Department of Invertebrate Zoology
"The meeting of minds between this and the next generation of natural scientists has made this internship an amazingly rich and rewarding experience!"

Survey of azooxanthellate corals (Scleractinia) attached by deep water Xenophora (Mollusca: Gastropoda), with a summary and analysis of the various theories for attachment behavior

ABSTRACT
The word "xenophora" derives from the Greek words meaning "foreign/alien" and "to carry." The gastropods that bear this name (mollusk Family Xenophoridae), known in English as carrier shells, possess the remarkable habit of attaching foreign objects to the tops of their shells. An astonishingly diverse collection of objects has been found attached to Xenophora, including (but not limited to) coral skeletons, bivalve and other mollusk shells, bryozoans, sharks' teeth and a wide array of inorganic debris. Because the bottom-dwelling fauna of the deeper ocean is known only from dredging and brief submersible excursions, deep water Xenophora are of special interest due to their largely unexploited potential as proxy collectors. The corals that could potentially be attached to such a Xenophora are called "azooxanthellate corals" because they lack the symbiotic algae (zooxanthellae) that characterize their shallow-water counterparts. The azooxanthellate coral fauna is not thoroughly known, and dredging is believed to provide an incomplete picture of diversity. In this study, over 200 deep water Xenophora shells from the collections of four museums were examined for attached coral skeletons. The 75 distinct coral phenotypes encountered included two previously unknown species and at least two maximum size records for known species. In addition, the occurrence of corals on Xenophora from various sites significantly expanded the known geographic ranges of 29 coral species. Examination of the attached corals revealed patterns in the manner of attachment, provoking a number of questions about the purposes and origins of the attachment behavior. The existing hypotheses were summarized and contrasted as a corollary of this study, and new data were gathered in hopes of shedding light on the problem. Although a number of the hypotheses seemed unlikely in the context of these observations, a conclusion cannot realistically be drawn without observation of living Xenophora or more extensive morphometric analysis.

This research was supported by a grant from the National Science Foundation Research Experiences for Undergraduates program, Award Number DBI-9531331.

Letter of Gratitude