A Mouth Bigger Than the Rest of It
The gulper eel (Eurypharynx pelecanoides) — also called the pelican eel — is one of the strangest fish in the ocean. Its most defining feature is immediately obvious: a massive, loosely hinged jaw that can open wide enough to swallow prey considerably larger than the eel’s own body. The mouth and stomach are elastic enough to expand dramatically, making the gulper eel one of the most extreme examples of predatory adaptation in the deep sea.
Anatomy
The gulper eel’s body is long and whip-like — adults reach 75–100 cm — but the head is dominated by the enormous jaws, giving it a comically top-heavy appearance. The lower jaw is loosely attached and can swing open at nearly a 180-degree angle. Behind the jaws, the stomach is highly expandable — when a large prey item is captured, the eel’s midsection balloons outward to accommodate it.
The tail ends in a complex of photophores — light-producing organs — that glow pink or red and are thought to be used as a lure, attracting curious prey toward the eel’s enormous open mouth in the darkness of the deep sea.
Habitat and Depth
Gulper eels inhabit the mesopelagic and bathypelagic zones — primarily 500–3,000 meters depth — in all major ocean basins. They are most commonly encountered between 1,000–1,800 meters. At these depths, food is scarce and unpredictable, which explains the extreme jaw and stomach adaptations: when a meal appears, the gulper eel needs to be able to take advantage of it regardless of size.
Diet
Despite its terrifying appearance, the gulper eel’s teeth are small and not well-suited for large, struggling prey. Analysis of stomach contents suggests it feeds primarily on small crustaceans, squid, and fish — not the enormous prey its mouth could theoretically accommodate. The giant mouth may serve more as a net than a trap, allowing the eel to engulf clouds of small shrimp or other crustaceans in a single pass.
FAQs
How deep does the gulper eel live?
Primarily 500–3,000 meters, most commonly around 1,000–1,800 meters depth.
Can a gulper eel really swallow prey larger than itself?
Its expandable jaws and stomach can accommodate prey larger than its resting body size, though in practice it appears to feed mainly on small prey items.