Alarm predators by releasing luminescent phytoplankton from your pores.
(Vids from Loghan Call, Joel Puckett, Peter Kragh and Avrilia Anggraeni)
A passage from Lord of the Flies, by William Golding.
"Along the shoreward edge of the shallows the advancing clearness was full of strange, moonbeam-bodied creatures with fiery eyes. Here and there a larger pebble clung to its own air and was covered with a coat of pearls. The tide swelled in over the rain-pitted sand and smoothed everything with a layer of silver. Now it touched the first of the stains that seeped from the broken body and the creatures made a moving patch of light as they gathered at the edge. The water rose farther and dressed Simon's coarse hair with brightness. The line of his cheek silvered and the turn of his shoulder became sculptured marble. The strange attendant creatures, with their fiery eyes and trailing vapors, busied themselves round his head. The body lifted a fraction of an inch from the sand and a bubble of air escaped from the mouth with a wet plop. Then it turned gently in the water.
Somewhere over the darkened curve of the world the sun and moon were pulling, and the film of water on the earth planet was held, bulging slightly on one side while the solid core turned. The great wave of the tide moved farther along the island and the water lifted. Softly, surrounded by a fringe of inquisitive bright creatures, itself a silver shape beneath the steadfast constellations, Simon's dead body moved out toward the open sea"
Bonus bioluminescent squid: