Master of Science
Dr. Jeffrey Hoch
Dr. Joshua Feingold
Dr. Omar Eldakar
This research addresses the knowledge gap of phenotypic plasticity in a commonly found and important species of epizoic barnacle, Chelonibia testudinaria. Limited research has been published regarding how phenotypic expression is mediated the spatial distribution of barnacles on a mobile host. To investigate this potential relationship, barnacles were collected from the backs of turtles along the beaches of Fort Lauderdale Florida. These barnacles were assessed for various phenotypic traits as well as their corresponding spatial distribution on the turtle carapace. Barnacles were safely removed from the carapace using a chisel before their preservation in ethanol. Barnacles were then numbered according to position on the carapace, then dissected, measured, and photographed under a microscope. Barnacles of clustered communities were fertilized at 68% greater rates than solitary individuals. To determine spatial distribution, each turtle’s carapace was separated into four different positions. Overall, barnacles were more abundant in the posterior position, followed by central, central costal and anterior scutes. Diameter, total length, and annulation/segmentation was measured for each barnacle’s penis, as well as their first cirri and sixth cirri. ANOVAS, factorial ANCOVAS, and logistical regressions were used to determine how functional morphology of the penis and feeding cirri change dependent upon different environmental and physical conditions. Internal body weight and position on the carapace were associated with penis morphology such that larger barnacles bear larger penises. Central costal barnacles possess a penis 27% larger compared to those settled on the anterior portion of the carapace. Feeding structures were also significantly different between individuals of different internal body weight, position and whether the barnacle was considered solitary. Larger barnacles have larger feeding cirri. Anterior barnacle's cirrus 1 segmentations were lesser when compared to all other positions. Crowded barnacles were observed to have thicker cirrus 1, compared to solitary individuals. Posterior barnacles have longer cirrus 6 compared to central costal individuals. While similarities between C. testudinaria and other species of acorn barnacles were expected, there are some notable differences. C. testudinaria seemingly did not adjust their morphology to combat the harsher environmental impacts of the high flow conditions experienced at the anterior portion of the turtle carapace. Barnacles residing within their preferred location of the posterior portion of the turtle carapace demonstrated morphological adjustments of their sixth cirri. Crowded individuals had thicker first cirri, likely accommodating for eddying caused by surrounding barnacles. Lastly, rather than adjusting their structural morphology in response to local condition, it appears that C. testudinaria rely on increased recruitment and simply move to a more desired location.
Kevin C. Cash. 2021. Resource Allocation and Phenotypic Plasticity of Simultaneous Hermaphroditic Turtle Barnacles (Chelonibia testudinaria). Master's thesis. Nova Southeastern University. Retrieved from NSUWorks, . (60)