Fluorescent Enhancement of Signaling in a Mantis Shrimp

Visual signals based on colored pigments can be unreliable in aquatic environments, because the optical properties of water spectrally filter both the incident and the reflected light. Fluo-rescence has more potential to contribute to color underwater than in terrestrial situations, because the spectrum of the emitted light can contrast effectively with that of the predomi-nantly blue illumination (1). Many corals have striking fluorescent coloration (2), and some vision-centered marine organisms such as squids have fluorescent patches (3). Though a behavioral function has been shown for fluores-cence in budgerigar plumage (4), the use of fluorescent colors as signals has not been