Lars Henrik Poding , Peter Jägers, Mareike Huhn, Stefan Herlitze

Fluorescence in marine animals has mainly been studied in Cnidaria but is found in many different phyla such as Annelida, Crustacea, Mollusca, and Chordata. While many fluorescent proteins and molecules have been identified, very little information is available about the biological function of fluorescence. In this review, we focus on describing the occurrence of fluorescence in marine animals and the behavioural and physiological functions of fluorescent molecules based on experimental approaches. These biological functions of fluorescence range from prey and symbiont attraction, photoprotection, photoenhancement, stress mitigation, mimicry, aposematism to inter- and intraspecific communication. We provide a comprehensive list of marine taxa that utilize fluorescence, including demonstrated effects on behavioural or physiological responses. On one hand, this review describes the numerous known functions of fluorescence in anthozoans and their underlying molecular mechanisms in detail. On the other hand, it highlights which marine taxa should be further studied regarding their functions of fluorescence. We suggest that an increase in research effort in this field could contribute to understanding the capacity of marine animals in responding to negative effects of climate change, such as rising sea temperatures and increasing intensities of solar irradiation.