The frilled shark, Chlamydoselachus anguineus, is an ancient deep-sea creature that has roamed the ocean depths for millions of years. Often referred to as a “living fossil” due to its primitive, eel-like physical characteristics, this species remains largely enigmatic. Its elusive nature and preferred habitat in the deep, dark reaches of the ocean make it a subject of ongoing scientific fascination.
Primary Prey
The diet of the frilled shark primarily consists of cephalopods, such as squid and octopus, alongside other smaller sharks and various deep-sea bony fishes. Squid can constitute a significant portion of their diet, sometimes as much as 60% in certain areas like Suruga Bay. Frilled sharks consume not only slow-moving, deep-dwelling squid but also larger, more powerful swimmers. Stomach contents have revealed that these sharks prey on other smaller sharks, with one instance showing a 1.6-meter frilled shark having swallowed an entire 590-gram Japanese catshark.
Frilled sharks can swallow prey whole, even if the meal is up to half their own body size. Despite their predatory nature, studies of captured individuals often find little to no identifiable stomach contents, suggesting either a fast digestion rate or extended periods between feedings. Some evidence also indicates they may consume carrion, supplementing their diet with dead organic matter. This varied diet supports the frilled shark’s role as a specialized predator within deep-sea ecosystems.
Hunting Techniques
Frilled sharks are ambush predators, utilizing their physical adaptations to capture prey in the low-light conditions of the deep sea. Their slender, eel-like body allows them to move in a serpentine fashion, crucial for their hunting strategy. They coil their bodies like a spring, bracing themselves with their rear fins, before launching quick, snake-like strikes forward to surprise unsuspecting prey. This sudden burst of movement helps them capture fast-moving or vulnerable creatures.
The frilled shark’s jaws are long and flexible, positioned at the very front of its snout, unlike most sharks whose jaws are underslung. This terminal mouth allows them to open their jaws wide, facilitating the swallowing of large prey in a single gulp. They also possess numerous rows of sharp, needle-like teeth, numbering around 300 trident-shaped teeth. These recurved, backward-pointing teeth function much like fishing hooks, effectively snagging and holding onto slippery prey. The contrast of their white teeth against their dark mouths may even lure prey closer.
Frilled sharks can also close their gill slits to create negative internal pressure, enabling them to suck prey quickly into their mouths. Their “open” lateral line system also enhances their hunting efficiency by detecting minute movements and vibrations in the water, even in complete darkness.
Deep-Sea Habitat Influence
The frilled shark’s deep-sea environment shapes its diet and feeding behaviors. These sharks inhabit depths ranging from 120 to 1,280 meters, where conditions are characterized by low light, cold temperatures, and immense pressure. Food is scarce in these extreme environments, necessitating specialized adaptations for survival.
Frilled sharks have developed a reduced, poorly-calcified skeleton and a large, oil-filled liver, which provide buoyancy and allow them to hover effortlessly in the water column. This buoyancy helps conserve energy, allowing the shark to wait patiently for the opportune moment to ambush prey. Their metabolism is also slow, an adaptation to the cold temperatures and sparse food resources of their deep-sea home. Frilled sharks may also undertake diel vertical migration, ascending to shallower waters during the night to feed on prey that migrates upwards. This behavior provides access to a broader variety of prey species, reflecting how their environment influences their feeding strategies.