Reef fish get riled when intruders glow red
Male fairy wrasses get feisty when a rival fluoresces
![](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2014/05/sm_fluor_feat.jpg?fit=860%2C460&ssl=1)
RED MESSAGE In the mostly blue world of a coral reef, a male fairy wrasse (left, illuminated with white light) will take note when one of its kind sports a fluorescent red glow (right, under blue light).
T. Gerlach et al/Proc. Roy. Soc. B. 2014