Photoblepharon. This fish has a pouch under the eye in which it cultivates bioluminescent bacteria. It uses its light organ to attract plankton at night and to communicate by emitting light signals by means of a light tight shutter in front of the light organ which it can move up and down (Gulf of Aqaba).

 

Sea feather. Like most stinging sea organisms, the sea feather harbors symbionts which profit from its protection (Philippines).

 

Symbiosis crabs are on the sea feather seen above. They catch plankton with their mouth parts which have developed into plankton nets (clearly visible in the picture). (Philippines).