An evolutionary oddity on the seafloor
The red-lipped batfish (Ogcocephalus darwini) is a fish that defies expectations. Found on the sandy bottoms around the Galápagos Islands, it has largely abandoned swimming for a more terrestrial form of movement. This fish uses its pectoral, pelvic, and anal fins, which are highly adapted, to "walk" across the ocean floor. This strange gait allows it to navigate the rubble and sand of its habitat at depths ranging from 3 to 76 meters.
Its body is not built for efficient swimming. The flattened, disc-like shape creates drag, and when startled, its swimming appears awkward and clumsy. Instead of fleeing, it relies on its unique locomotion and camouflage. The fish's light brown and grayish dorsal side, often with a dark stripe of brown dots, helps it blend in with the seabed. This combination of walking and camouflage makes it an effective ambush predator, a necessity for a creature that cannot chase down its food. The fish's anatomy is suited for this lifestyle, with a body structure supported by 19 to 20 vertebrae.
A very specialized hunter
The red-lipped batfish belongs to the anglerfish order, Lophiiformes, and possesses a characteristic lure for hunting. When the batfish matures, its dorsal fin transforms into a single, spine-like projection called an illicium. At the tip of this illicium is a fleshy esca. Unlike many deep-sea anglerfish whose lures are bioluminescent, the batfish's esca is thought to excrete a chemical that attracts small prey. The fish can extend and retract this lure, which is protected by an elongated snout, to entice small fish, shrimps, crabs, and mollusks.
The purpose of its most famous feature—the bright red lips—is still a subject of scientific study. One leading hypothesis suggests the lips are used for species recognition, particularly during spawning. They may also help with attracting mates. This fish, which can grow to about 40 centimeters in length, combines its unusual locomotion with specialized hunting tools to survive in its unique marine environment.