Symbiosis — Definition & Types

Adult female anglerfish have an organ called an esca, which resembles a fishing rod. The tip of the esca is bioluminescent and the anglerfish uses the glow to attract mates and prey. The anglerfish doesn't make the tip glow by itself, rather a specific type of bioluminescent bacteria living in and around the esca causes the glowing. The anglerfish has some molecules that the bacteria needs but can't make by itself.