Anglerfish are creatures that often spark curiosity due to their distinctive appearance and the mysterious depths they inhabit. These fish are widely recognized for the glowing lure extending from their heads, a feature commonly associated with the dark, extreme environment of the deep ocean. This leads to a natural question: can these fascinating fish survive in the comparatively bright and warm conditions of shallow water? The answer depends on the specific type of anglerfish, as not all species are adapted to the same aquatic realms.
Deep-Sea Anglerfish: Masters of the Abyss
Deep-sea anglerfish (suborder Ceratioidei) thrive in the profound darkness of the bathypelagic zone, at depths from 200 to over 2,000 meters. Their most notable adaptation is a modified dorsal fin ray, called an illicium, which ends in a fleshy lure known as an esca. This esca contains bioluminescent bacteria, producing light to attract prey like small fish and crustaceans.
These fish have flexible bones and expandable stomachs, allowing them to consume prey up to twice their size. Their bodies withstand immense pressure and are found in frigid waters, typically 2°C to 12°C (36°F to 54°F). Deep-sea anglerfish often have dark coloration, from grey to brown, helping them blend into their dark surroundings.
Why Shallow Water is Hostile for Deep-Sea Anglerfish
Bringing a deep-sea anglerfish to shallow waters would be detrimental due to drastic environmental changes. Their bodies are adapted to endure crushing pressures, exceeding 1,000 times atmospheric pressure. A rapid decrease in pressure would cause severe internal damage and organ failure, as their internal pressure, adapted to the deep, would greatly exceed external pressure.
Warmer shallow water temperatures would disrupt their physiology, as their metabolisms are accustomed to near-freezing deep-sea conditions. Deep-sea anglerfish are adapted to perpetual darkness; exposure to sunlight would overwhelm their sensitive eyes. The shallow-water ecosystem also presents unfamiliar food sources and different predators, to which these specialized deep-sea inhabitants are not adapted.
Anglerfish That Call Shallow Waters Home
While deep-sea anglerfish cannot survive in shallow environments, not all anglerfish species reside in the abyss. The order Lophiiformes comprises over 200 species found across various depths and habitats. Some families, such as Antennariidae (frogfish) and Lophiidae (goosefish or monkfish), are well-known shallow-water inhabitants.
Frogfish are found in tropical and subtropical coastal marine waters, including coral reefs and rocky bottoms, at depths of 3 to 45 meters (10 to 150 feet). Shallow-water anglerfish do not use bioluminescent lures; instead, their lures mimic small prey like worms or shrimp, attracting fish in well-lit conditions. Many shallow-water anglerfish species use camouflage, changing skin color and texture to blend with surroundings, appearing like rocks, sponges, or seaweed. They use modified pectoral fins to “walk” along the seafloor, ambushing prey.