Avery Thomson

Date of Award

2012

Document Type

Thesis

Degree Name

Bachelors

Department

Natural Sciences

First Advisor

Demski, Leo

Keywords

Lepomis, Autonomic, Chromatophore

Area of Concentration

Neurobiology

Abstract

Certain fishes are unique in their ability to display skin color changes that reflect certain behavioral states. The vertical banding pattern (VB), the appearance of seven to nine dark vertical bands on the side of the fish, is a visual signal exhibited by certain percomorph fishes when they "feel" threatened. The bluegill centrarchid (Lepomis macrochirus) exhibits robust VB. Brain areas have been mapped for VB in centrarchids . The sympathetic nervous system is likely controlling the lightening/darkening of sets of chromatophores required for VB display. These cellular elements have been defined in cichlid fishes. This study visually confirms the similarity of the described cichlid systems with those of living cichlids, Hemichromis bimaculatus and Oreochromis aureus and living bluegills. System II (Baerends and Baerends-Van Roon,1950) and System III (Lanzing and Bower, 1974) were confirmed as the major contributors in VB display. Establishment of these systems as the effectors of bluegill VB allows for greater elucidation of the entire chromatomotor pathway in centrarchids. Additional research may determine whether or not the VB pathway is universal in percomorphs and the information obtained in fishes can be used as a general model for sympathetic nervous system involvement in defensive behavior.

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