The pelican eel, a rarely seen deep-sea fish known scientifically as Eurypharynx pelecanoides, can stretch its mouth wider than its own head in order to swallow large prey, according to facts published by BBC Wildlife Magazine.
The fish was first discovered in 1882 and is seen so infrequently that only a small number of researchers taking part in deep-sea expeditions have ever caught a glimpse of the animal in its natural habitat, the magazine reported. The species belongs to a family of deep-sea fish commonly known as gulper eels, valued by marine biologists for their extreme adaptations to life in permanent darkness.
A Mouth Built for Huge Meals
The pelican eel gets its name from its ability to stretch its mouth wide enough to hold a very large amount of food, BBC Wildlife Magazine said. The mouth can expand like a balloon, or like a pelican's beak, and when it is not inflated the fish reveals a long, thin, eel-like body that ripples through the water as it moves.
The animal is black in colour, with a thin white stripe sometimes running along its dorsal fin. The tip of its tail carries a red or pink glow produced by bioluminescence.
Life Between 500 and 3,000 Metres
Pelican eels live at depths of between 500 and 3,000 metres in tropical and temperate waters around the world, the magazine said. Little or no sunlight reaches these depths, and the creatures that live there have had to adapt in order to survive.
Below 1,000 metres, the only light available comes from bioluminescent animals, of which the pelican eel is one, according to the magazine.
Its lower jaw makes up roughly a quarter of its total body length and has a hinge that allows it to open even wider. Along with its prey, the fish swallows a mouthful of water, which is then filtered back out through its gills.
BBC Wildlife Magazine said this ability lets the pelican eel swallow large animals such as squid, or an entire group of shrimp and other small crustaceans, in one go. At times, the magazine added, the fish eats prey larger than itself.
A Poor Swimmer With Tiny Eyes
Despite its fearsome bite, the pelican eel is far from a strong swimmer, the magazine said. It has no scales, no pelvic fins and no swim bladder, and moves through the water by undulating its thin tail in a wave-like motion.
Its eyes are also very small, making it difficult for the fish to spot prey, in contrast to many other deep-sea fish, which tend to have large, staring eyes. BBC Wildlife Magazine noted that, unlike many other deep-sea species, the pelican eel does not migrate towards the surface, where food is more plentiful, and suggested this may be linked to its weak swimming ability.
Still Largely a Mystery
Scientists still know relatively little about the species. Researchers have established that pelican eels grow to an average body length of up to 80 centimetres, but how long they live remains unknown, according to the magazine.
Separately, IFLScience has reported on another long-lived fish, the lake sturgeon, which can live for more than 400 years. That lifespan places the species among the longest-lived fish known to science, alongside the Greenland shark, IFLScience said.
