Sensory Biology of Coral Reef Butterflyfishes:

        The Laterophysic Connection

 

 

Supported by NSF grant IBN 9603896 to Dr. Jacqueline F. Webb, Villanova University (1997-2000)  and Collaborative NSF Grants IBN 0132607 Dr. Jacqueline F. Webb and IBN 0137883 to Dr. Timothy C. Tricas,

University of Hawaii (2002- 2006)

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Introduction to the Project

Butterflyfishes of the genus Chaetodon (Family Chaetodontidae) are conspicuous and important components of coral reef communities and are ecological indicators of reef health due to their dependence on coral as a food source.  These fishes exhibit a wide range of social and feeding behaviors and their species-specific color patterns provide visual cues used in social communication, but until recently these fishes were not known to produce sound during natural social behaviors. We have shown  that territorial butterflyfishes produce sounds during agonistic interactions in the field (Tricas lab).  Normally the ear is the organ responsive to sound (as in all vertebrates).  In  fishes of the genus Chaetodon,  however, it appears that the mechanosensory lateral line system, which is normally responsive only to water flow, may also be sensitive to sound.  This is thought to be due to the presence of a  unique  linkage of the swim bladder with the lateral line system (the laterophysic connection),  which is found only in fishes in the genus Chaetodon.

            With prior NSF funding to the Webb lab (1997-2000) we defined the morphological variation in the laterophysic connection among species, how it has evolved within the genus Chaetodon and how it develops during the larval and juvenile stages.

The goal of our current NSF grant is to understand the functional significance of this unique structural specialization and the ways in which the ear and lateral line system process and integrate sounds produced during natural social behaviors.  In order to accomplish this, the Webb (Villanova U. ) and Tricas (U. Hawaii) labs are studying several species of Chaetodon and testing the more specific hypotheses that:

1) butterflyfishes in the genus Chaetodon produce sound in the context of specific behavioral interactions in the field,

2) the presence of swim bladder horns enhances sensitivity of the inner ear to sound pressure stimuli,

3) the laterophysic connection makes the lateral line system sound-sensitive, where it is normally only sensitive to water flow (which is physically distinct from sound), and

4) variation in the structure of the laterophysic connection has important functional implications for the degree of sound sensitivity. 

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