The goblin shark (Mitsukurina owstoni) is a mysterious deep-sea creature known for its distinctive appearance. Often called a “living fossil,” its most striking characteristic is its unique, protruding jaw, which sets it apart from other shark species. This article explores how this remarkable jaw functions.
The Goblin Shark’s Deep-Sea Home
Goblin sharks inhabit the deep ocean, typically found at depths between 100 and 1,200 meters (330 to 3,940 feet), where sunlight does not penetrate. This environment presents challenges like low light and scarce prey, leading to specialized adaptations. The goblin shark’s pinkish body coloration, resulting from translucent skin and visible blood vessels, serves as camouflage in this low-light setting. Its unusual jaw structure is one such adaptation, aiding survival in these challenging depths.
Anatomy of the Protruding Jaw
The goblin shark’s jaw is loosely attached to its skull, held primarily by ligaments and muscles rather than rigid tissue and bone. When at rest, the jaws retract towards the underside of its head. The upper and lower jaws can rapidly shoot forward, extending several feet. Its slender, sharply recurved teeth are “nail-like,” pointing backward to impale and hold prey. This loose attachment allows for mobility, differing significantly from the firmly anchored jaws of most other shark species.
How the Jaw Operates
The goblin shark’s jaw operates through a rapid, coordinated movement of muscles and ligaments, allowing it to shoot out from the head. The loose ligaments and tendons anchoring the jaws act like elastic bands, building tension when pulled back and releasing quickly to propel them forward. This biomechanical process is often described as a “slingshot mechanism” or “catapult action.”
Powerful muscles surrounding the jaws contract rapidly, providing the force for extension. The lower jaw moves approximately twice as fast as the upper jaw, swinging upward to aid in prey capture. This allows the goblin shark to snatch prey swiftly, with jaw extension reaching 1 to 9.5 times farther than in related species. The jaw can project at speeds up to 3.1 meters per second, among the fastest recorded for a fish.
Feeding with the Unique Jaw
The goblin shark employs a “protrusion feeding” or “jaw-thrust” strategy, ambushing prey by rapidly extending its jaws. This stealth hunter drifts quietly, waiting for fish, squid, or crustaceans to come within close proximity. Once prey is detected, the jaws thrust forward, extending up to three times the length of its head.
Inside the goblin shark’s mouth, a tongue-like structure called the basihyal drops down as the jaws extend. This action expands the mouth, creating a suction force that pulls prey in along with water. This adaptation is effective in the dark, low-visibility deep ocean, allowing the shark to snatch prey and compensating for its slow swimming speed.