A study explores how clownfish gain their distinctive white bars. Charismatic denizens of coral reefs, clownfish are easily spotted by the sinuous white bars that lend their streamlined bodies a striped appearance. The white bars develop during metamorphosis, but the driving factors remain unclear. Vincent Laudet and colleagues report that the rate of white bar formation in the clownfish Amphiprion percula, which lives in symbiosis with two different sea anemone hosts in the tropical waters of Kimbe Bay, Papua New Guinea, varies depending on the host species. New recruits of A. percula found in the anemone host Stichodactyla gigantea exhibited more white bars--as well as earlier development of white bars--than those of similar age and size found in the anemone host Heteractis magnifica. Experiments in which larval clownfish were exposed to varying concentrations of thyroid hormone (TH) revealed that TH acts on color-producing cells called iridophores and influences white bar development in a dose-dependent manner; blocking TH delayed white bar formation. Comparison of gene expression in A. percula recruits in the two hosts uncovered a role for the duox gene, which encodes the enzyme dual oxidase, implicated in TH production; duox was overexpressed in new S. gigantea recruits, compared with new H. magnifica recruits. Although the ecological significance of white bar formation remains unclear, the findings raise the possibility that TH-driven bar formation in clownfish may be tied to their differential recruitment in and adjustment to different sea anemone species, according to the authors.
High resolution images, along with caption are credit information can be found at: https://drive.google.com/drive/folders/1gu-O4bEbsUyV_z6bJ3MIZJx_mheb_fjl?usp=sharing
Article #21-01634: "Thyroid hormones regulate the formation and environmental plasticity of white bars in clownfishes," by Pauline Salis et al.
MEDIA CONTACT: Vincent Laudet, Okinawa Institute of Science and Technology, Okinawa, JAPAN; tel: +818098520005; email: vincent.laudet@oist.jp
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Journal
Proceedings of the National Academy of Sciences