Date of Award

2018

Document Type

Open Access Thesis

Department

Marine Science

Sub-Department

College of Arts and Sciences

First Advisor

Daniel I. Speiser

Abstract

Conch are slow-moving, herbivorous, marine gastropods that possess prominent camera-type eyes at the ends of long, flexible stalks. Compared to the eyes of other gastropods, those of conch are large (up to 1.5 mm in diameter) and have sophisticated optics that include a lens with a graded refractive index. Conch also have a remarkable ability to regenerate eye tissue: after an eye is lost, a new eye will develop to take its place within weeks. Eye regeneration in conch appears to occur rapidly compared to eye regeneration in other gastropods. Despite our knowledge of the complexity and regenerative abilities of the eyes of conch, we know little about the visual responses of these animals either when their eyes are intact or while they are regenerating. Therefore, we measured rates of eye regrowth and tested how visual performance changes during the process of eye regeneration in the Florida fighting conch, Strombus alatus. We found that rates of eye regrowth were greatest in S. alatus between 3-6 weeks following eye removal but began to slow down thereafter. We also found that conch with two intact eyes respond consistently to moving objects with angular sizes of 24° or greater and angular speeds between 27 and 82 °/s. We removed either one or both eyes from 24 conch and recorded the behavioral responses of these animals to visual stimuli once a week for twelve weeks. We found that the visual performance of conch with the left eye removed never declined to begin with, suggesting that they successfully compensated with their intact right eye. However, the visual performance of conch with the right eye and both eyes removed declined immediately following eye removal but was regained four weeks and seven weeks thereafter, respectively. To learn more about the process of eye regeneration in conch, we used immunohistochemistry to visualize the expression of phototransduction proteins at different stages of eye regeneration. In the 4th week of eye regeneration, rhodopsin and Gq proteins were found to be present which suggests the return of visual performance. By studying the restoration of visual performance during eye regeneration in conch we will continue to gain more understanding of how a regenerating sensory system reconnects with an intact nervous system.

Rights

© 2018, Jamie M. Clark

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