We would like to thank the crews of the submersibles Johnson Sea Link I and II, and the R/V Johnson, Seward Johnson, and Edwin Link for their help, support, and excellent ship and sub handling. Thanks are due to T. Askew, head of Marine Operations at the Harbor Branch Oceanographic Institute, Ft. Pierce, FL, who facilitated the scheduling of our cruises, and to W.I. Ausich (Ohio State Univ.), D.L. Meyer (Univ. Cincinnati), R. Mooi (California Academy of Sciences), A. Seilacher (Yale University), R. Lewis (Auburn University), C. Maples (Univ. Kansas), B.J. Greenstein (Cornell College), J. McClintock (Univ. Alabama, Birmingham), E. Balser (Illinois Wesleyan Univ.), and A. Smith (Natural History Museum, London) who participated in our cruises and contributed some excellent discussions about these animals. Former NSU graduate students who also contributed include C. Featherstone, P. Bellew, D.L. Rankin, C.M. White, R. Sherman, S. Thornton, H. Balchowsky and D. Gilliam. We also thank two anonymous reviewers for their comments. These research results derive from funding provided under National Science Foundation grants EAR-9004232, EAR-9218467, EAR-9628215 (CGM), and EAR 9104892; 9304789 (TKB).