This chain catshark dwells in the dark night of the deep sea. But without a yellow filter to block out blue light—which some biofluorescent fish have—these neon colors would be invisible.
This flatfish flashes a fiery orange-red on its back (pictured), but shows off a green fluorescent pattern on its belly.
Marine biologist David Gruber first noticed biofluorescence in fish when a green eel (similar to the one pictured) photobombed him and colleagues as they took pictures of biofluorescent coral.
Biofluorescence could be employed for a number of reasons, says Alexander Gaos, director of the Eastern Pacific Hawksbill Initiative. They include finding or attracting prey, defence, or some kind of communication.
This bright red scorpionfish (center, left) employs biofluorescence to blend into the neon green and red coral reef the fish calls home.
Like the hawksbill sea turtle, this seahorse gives off more than one color. The fish is mostly red while sporting bright green highlights around its eyes. The green also appears in speckles on other parts of the seahorse's body.
Under white lighting conditions, the stripes on this bream appear yellow. But turn on some blue light and attach a yellow filter to a camera to catch fluorescence, and you get the next photo.
This bream is the same one from the previous picture—it's just been photographed so that the fluorescence is visible to us. Scientists are just starting to figure out why biofluorescence is so widespread in the ocean.
