Fluorescence patterns and diversity of hydrozoans from Bocas del Toro, Panama

Abstract

Many metazoans contain molecules capable of fluorescence, the absorption and re-emission of light. Since the anatomical distribution, or patterning, of these molecules is variable across taxa, patterns of fluorescence may serve as a powerful diagnostic tool in taxonomy and ecology. However, species-specific fluorescence patterns among marine invertebrates are poorly understood. Here, we show that hydrozoans have diverse fluorescence patterns, which may result from molecules that are produced intrinsically or obtained from dietary sources. We surveyed hydrozoans including siphonophores, hydromedusae, and hydroids across 5 orders from pelagic and benthic marine environments in Bocas del Toro, Panama. Our findings show that fluorescence patterns are highly prevalent and may vary across hydrozoan species and throughout development. Most of the examined hydrozoan taxa exhibited some form of fluorescence, with variation observed between life stages and body parts. Fluorescence was documented in 88% of  hydromedusae (Leptothecata, Anthoathecata, Limnomedusae and Narcomedusae), 50% of hydroid, and 75% of siphonophore taxa that were observed in this study. Our results illustrate how fluorescence patterns may serve as a useful diagnostic tool to explore marine biodiversity, highlighting the need for further documentation of fluorescence patterns across marine diversity and research into the molecules that underlie this phenomenon.