Dehm, Jascha (2015) Does wearing a hat change the demeanour of a fish? A behavioural study of the manipulation of active photolocation in the benthis fish Tripterygion delaisi. (Master thesis), Christian-Albrechts-Universität zu Kiel, Kiel, Germany, 33 pp.

Text MSc. 2015 Dehm,J.pdf - Reprinted Version Restricted to Registered users only Available under License German copyright act UrhG. Download (4MB) | Contact

Abstract

In very few confirmed cases, features exist which allow fish to enhance vision by using and manipulating light. Although definite reasons for this are unknown, it has been suggested this is used to locate prey items. Recent studies suggest that the triplefin blenny, Tripterygion delaisi, uses methods of "active photolocation" to stimulate eyeshine in potential prey items. To further investigate methods and reasons behind active photolocation, the process of active photolocation needs to be manipulated. One such method involves the use of plastic light filters in the shape of a hat, which is attached to the head of a specimen and hence manipulates downwelling light. This study is based on determining whether the manipulation of active photolocation through the use of filters hats, has an effect on the behaviour of T. delaisi. Results show that the use of filter hats, successfully hinders at least one aspect of active photolocation; the ocular spark. Apart from feeding related behaviour no other tested behavioural aspect is significantly influenced. A second test, aimed at determining if the inability to produce ocular sparks results in lower consumption of retroreflective prey items, failed to produce significant results to support this hypothesis. However, a third test which aimed at determining whether T. delaisi rely on vision rather than olfaction to detect a key predator, Scorpaena porcus, yielded surprising results. Apart from the results supporting this claim, it is clearly noticeable that when hindered from normal active photolocation, individuals tend to be much closer to S. porcus. This finding suggests that that active photolocation may not necessarily be used for finding prey but may also be employed in predator detection.

Actions (login required)

View Item