twenty- four hour cycle showed no obvious coordinated rhythm; 

 longer observational studies are needed to examine animal 

 behavior. One other difference between shallow and deep water 

 pennatulids is the rapidity with which they contract. On several 

 submersible dives, sea pens were either hit gently with the 

 submersible' s arm or observed to be hit by a crab scurrying out 

 of the sub's path. In both instances the sea pens showed no 

 immediate response. Only after persistent prodding with the arm 

 did one animal sluggishly, and only partially retract. Such 

 behavior is obviously of little value as a defense mechanism 

 suggesting that, perhaps, deep water sea pens are cued by 

 internal, physiological needs rather than external stimuli. 



The behavior of Pennatula also confounds a detailed 

 evaluation of the microscale distribution of the animals (Figures 

 3 and 4). The photographic, distributional data collected on a 

 single submersible dive, in the area of apparent highest sea pen 

 density in the Gulf, could not be described by either a Poisson 

 or negative binomial distribution. Although it is not possible 

 to know with any confidence, it may be that the contraction- 

 extension behavior biases these distributional patterns. In any 

 event, if a mathematical model were found to fit the data in 

 Figure 4, the biological meaning is suspect without a better 

 understanding of sea pen behavior. 



ACKNOWLEDGEMENTS 



Support for this work was received from NOAA's National 

 Undersea Research Program at the University of Connecticut, Avery 

 Point. We also thank Pat Shiers for typing the manuscript and 

 Jim Rollins for the graphics. 



LITERATURE CITED 



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Bayer, F.M. 1956. Octocorallia. Treatise on Invertebrate 



Paleontology Part T. Coelenterata. Geology Society of 

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Bayer, F.M. , M. Grasshoff and J. Verseveldt 1983. Illustrated 

 trilingual glossary of morphological and anatomical terms 

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Bigelow, H.B. 1927. Physical oceanography of the Gulf of Maine, 

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Birkeland, C. 1974. Interactions between a sea pen and seven of 

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