Date of Award


Document Type


Degree Name

Master of Science (M.S.) in Biology



Physical Description

1 online resource (65 p.)


Halosydna brevisetosa, Thelepus crispus




Chemical, physical and physiological interactions between the marine commensal scaleworm Halosydna brevisetosa Kinberg and its terebellid host, Thelepus crispus Johnson were investigated. In an experiment designed to test for chemical attraction between the host and commensal, Halosydna were unable to identify the arm in a U-tube choice apparatus leading to the host. In 50 trials, 54% of the commensals crawled into the flow of water from their hosts. Other observations showed that Halosydna made contact with the host by random encounter. After contact, commensals followed tentacles down into the host’s tube and took up a characteristic position along the dorsum of the host’s body wall. Halosydna’s specific orientation in the host’s tube may be the result of the current produced by the host rather than the presence of the host itself. Experiments with free-living forms of Halosydna revealed that these animals, not found in a commensal association, did not react to host tentacles, or to sea water containing several hosts.

The general purpose of this study was to investigate the commensal relationship between the polynoid Halosydna brevisetosa Kinberg and its terebellid host Thelepus crispus Johnson.


A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Biology

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