More than 200 species of biofluorescent fishes have now been recorded using a blue light source and custom-built underwater cameras that only image the longer wavelength light that is transformed by the animal. Species include both cartilaginous and bony fish. Biofluorescence is especially prevalent among cryptically patterned, well-camouflaged, shy species such as the chain catshark, pictured here, and other species of catsharks such as the swell shark. The precise function of biofluorescence is not fully known, although it is thought to be a form of communication between species that, unlike humans, have the visual apparatus to see the fluorescent patterns.
To excite a fluorescence response, the animals were illuminated with ultra-bright blue LED lights that are collimated to give out parallel rays of light in the range of 450 to 500 nm. The image was recorded with a camera with a filter that attenuates light below 514 nm.
David Gruber, PhD., Dept. of Biology and Environmental Sciences, Baruch College, City University of New York and Invertebrate Zoology/Sackler Institute of Comparative Genomics, American Museum of Natural History, New York.