Anglerfish

The majority of anglerfish live below the photic zone. The lack of light causes difficulties in both feeding and breeding, but the anglerfishes have overcome these problems. Anglerfish all have a 'fishing pole' that extends from the head and has a fleshy part on the end that is lit with bioluminescence and can be moved to resemble a prey item for other organisms. When a curious or hungry creature moves close enough to take a look at the lure, the anglerfish pounces, capturing the unwary victim.

Some anglerfish have a unique mating method. Without light, finding a mate is a problem, especially at a time when both individuals are ready to spawn. When scientists first started capturing members of a specific group of anglerfishes, they noticed that all of the specimens were females. These individuals were a few inches in size and almost all of them had what appeared to be parasites attached to them. It turns out that these were the males. When a male anglerfish is hatched, he has extremely well developed organs that detect scents in the water. He has no digestive system. His goal in life is to detect the pheremones[?] that the female anglerfishes release. When he finds a female (and if he doesn't, he dies), he bites into her flank which releases an enzyme that digests the skin of his mouth and her body. The two then fuse together, including blood vessels. The male degenerates into nothing more than a pair of gonads that releases sperm when the female releases hormones into the bloodstream that signals she is ready to release her eggs.