Anglerfish
The appendage, which resembles a fishing pole, is attached to the end of the dorsal fin's front spine, which is separated from the rest of the fin. Anglerfish light their rod with bioluminescence (their own light) and then wiggle it to mimic a small marine animal. When other creatures come to eat the small marine animal, the anglerfish eats them. They are called anglerfish because they catch fish with bait, just like anglers, who use a rod and line (rather than nets).