This video, shot over 1,700 ft down in the Gulf of Mexico, shows the fluorescence of a benthic sea spider. Using blue lights to illuminate the sea floor, and a video camera covered with a yellow filter, fluorescing benthic life glows into focus. Listen as the observer in the submersible -- who is wearing yellow goggles -- discovers the 6-in wide pycnogonid, films it, and finally demonstrates how difficult it would be to locate this small creature had they been using the standard white lights.