CIRRAL ACTIVITY AND FEEDING BEHAVIOR OF A LAB RAISED SEA TURTLE COMMENSAL <i>Chelonibia testudinaria</i> IN VARIABLE FLOW AND IN THE PRESENCE AND ABSENCE FOOD
Lane, Zachary Michael
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Barnacles are sessile suspension feeders whose feeding efficiency and behavior is largely determined by the movement of water through their environment. In low flow environments, where particle capture is difficult, barnacles expend energy to feed actively, while in higher flow environments barnacles may feed passively which is more efficient and effective than active feeding. Many intertidal barnacles have been shown to switch between active and passive feeding modes as water velocities increase, but little is known about epibiotic species which are exposed to variable feeding currents and possibly display different behavior than intertidal species. To better understand the behavior of epibiotic barnacles, a methodology was developed for rearing the sea turtle commensal <i>Chelonibia testudinaria</i> to adulthood in the laboratory. This technique made use of several specialized tanks to promote larval settlement and subsequent growth of barnacles on PVC pipes. Lab-reared adults (shell diameter = 12.63 ± 0.08 mm) were then subjected to a wide range of water velocities in a flume and their behaviors categorized and quantified with BORIS event logging software. Over the course of observation C. testudinaria displayed only passive feeding behavior, and at lower velocities, instead of switching to active feeding, did not feed at all. This species was most active between 20.63 cm s<sup>-1</sup> (Z = 5.6, p < 0.0001) and 53.59 cm s<sup>-1</sup> (Z = -11.62, p < 0.0001) as identified by logistic regression, a velocity range which correlates well with the average swimming speed of two common host species, loggerhead and green sea turtles, on which <i>C testudinaria</i> resides. Lack of active feeding in this species may have evolved in concert with its epibiotic habitus, making this species an obligate commensal, reliant on its hosts’ movement to provide flow for particle capture as adults. Further investigation into this and other epibiotic species may be merited. Such pursuits will be facilitated by the rearing and husbandry techniques developed herin.