Meeting Abstract
Daily patterns of activity in a majority of organisms are influenced by endogenous circadian clocks that entrain to external cues. Recently, the nudibranch Melibe leonina has been used for circadian studies due to its relatively simple central nervous system. However, this animal poses challenges to researchers, such as unreliable access to populations for study, and difficulties establishing breeding colonies due to diverse developmental needs of larvae vs adults. The nudibranch Berghia stephanieae is readily available in the marine pet trade as a predator of the invasive anemone Aiptasia pallida. Since B. stephanieae has direct development, successive generations of this nudibranch, as well as sufficient food supplies for all stages of growth, can be conveniently maintained in the laboratory. The goal of this study was to determine if B. stephanieae exhibits circadian rhythms of crawling. B. stephanieae were visually tracked over a seven-day experiment, with three days of normal light/dark cycles followed by four days of constant darkness. Animals exhibited an overwhelmingly nocturnal pattern of activity. All individuals that remained healthy during the entirety of the experiment also exhibited circadian rhythms of crawling that persisted in constant darkness with an average tau value of 21.1 ± 2.5 h (mean ± standard deviation). It was also discovered that B. stephanieae are capable of crawling out of the water for extended periods of time (e.g., close to an hour), suggesting possible intertidal adaptations. Based on this evidence, we recommend B. stephanieae as an organism for future studies of circadian rhythms at the genetic and neurological level.
