This is one alluring fish.

Food is scarce in the deep sea, so animals get creative to find a meal. Instead of chasing down prey, the deep-sea anglerfish (order Lophiiformes) goes fishing. 

The first ray of an anglerfish’s dorsal fin is modified into a filament like a fishing pole. At the tip is a sac of glowing bacteria, called an esca. Each species has a unique rod and lure—some have simple lures, some have elaborate ones, and some even have multiple lures. Hungry anglerfishes set out bioluminescent bait and wait. Their dark skin absorbs light, an ultra-black camouflage that helps mask their presence. The luminous lure entices small fishes and crustaceans to come closer, then the anglerfish’s massive mouth and sharp teeth snap shut for a meal.

In the ocean’s midnight zone, food is not the only thing that can be scarce. Mates can be hard to find in this endless expanse too, so some anglerfishes have a unique strategy for reproduction. The blobby, softball-sized anglerfishes are females. The males are dwarfs, growing to just a few centimeters. The tiny males have a strong sense of smell and follow pheromones to find females. In some, but not all, species, the males are parasitic, so when they encounter a mate, they permanently attach themselves to her body.

Deep-sea anglers may be most recognizable, but there are more than 200 anglerfish species in the order Lophiiformes. They come in all sorts of shapes and sizes, and occupy a variety of habitats. Sea toads (family Chaunacidae) and batfishes (family Ogcocephalidae) live on the deep seafloor, but some anglerfishes live in shallow water. Frogfishes (family Antennariidae) have vibrant colors to camouflage among the corals on tropical reefs, while speckled coloration helps goosefishes (family Lophiidae) blend into the sandy seafloor on the continental shelf. Just like their deep-sea kin, these anglers are ambush predators. But seafloor anglers do not use luminescence to fish for food. Instead, they flick a frilly, decorative lure to draw in potential prey.

In nearly four decades of ocean exploration with advanced underwater robots, MBARI scientists have logged just a handful of encounters with these unique fishes. Each observation sheds new light on these mysterious residents of the midnight zone, but inevitably raises new questions too.

Deep-sea anglerfishes and other residents of the midnight zone face a fragile future from actions on the seafloor far below. Mining the abyssal plain for manganese and other rare minerals will release a sediment plume that will cloud the waters above. Anglerfishes depend on clear water for their bioluminescence to effectively lure prey. We urgently need to understand how mining will affect all deep-sea animals. MBARI’s research is answering fundamental questions about the deep sea that will help resource managers and policymakers make informed decisions about the future of marine life, environments, and resources.