The Can-do Pelican Eel
The pelican eel, also known as the gulper eel (Eurypharynx pelecanoides), are the only known species of eel in the family Eurypharyngidae. They are found exclusively in the deeper parts of the water column, from depths of 500 up to to 3,000 m (1,600 to 9,800 ft), but are distributed throughout all the world's oceans.
The gulper eel is perhaps most famous for its unique body shape. Like many deep-sea fish, this species is highly adapted to its environment; maximum energy efficiency is the highest priority. To that end, the pelican eel has a large head, and a jaw estimated to be quarter of the total length of its body. The jaw is loosely hinged, meaning that gulper eels can open their mouths extremely wide. The rest of the eel, in contrast, is quite slender and long, about 0.75 m (2.5 ft) in length on average. Most individuals are black--so black, in fact, that they only reflect 0.5% of light; perfect for hiding from potential predators.
Although they look skinny, E. pelecanoides can expand their stomachs to hold prey much larger than themselves. Their primary prey consists of crustaceans and cephalopods, though they may feed opportunistically on other fish. Because it is so well camouflaged, it uses bioluminescent organs on the tip of its tail to attract prey. Gulper eels themselves are preyed upon by lancetfish and other larger deep-sea fish. To deter predators, they will gulp down a large amount of water; this stretches the loose skin around their head and throat, and inflates them to several times their usual size.
Because of their remote location, the breeding habits of gulper eels are relatively unknown. However, it is believed that smell plays a large part in attracting a mate, as pelican eels have highly developed olfactory organs. Like other eels, they're born as tiny, transparent larvae in a state known as the leptocephalus stage. At this stage, they do not have any red blood cells. Researchers aren't sure how long it takes gulper eels to become fully mature, or how long they live, but many believe that adults die shortly after mating.
Conservation status: The population size of E. pelecanoides has not been assessed, and thus the IUCN has not made a determination on its status. The greatest threat for this species is deep-sea trawling, which frequently brings up gulper eels as by-catch.
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