In a groundbreaking study published in Ocean-Land-Atmosphere Research, scientists have captured rare footage of an elusive deep-sea predator exhibiting unusual behaviors in waters far from its typical habitat. The footage, recorded 5,345 feet (1,629 meters) beneath the surface of the South China Sea, has left marine biologists astonished as the predator, previously believed to inhabit only cold, northern waters, was spotted in tropical latitudes.

This unexpected appearance challenges prior assumptions about the species’ geographic distribution and provides valuable insights into its survival tactics in the deep ocean. Researchers had initially set out to study the natural process of whale fall, where carcasses sink to the ocean floor, attracting deep-sea scavengers. Instead, they unintentionally captured footage of the predator’s feeding behaviors, revealing key information about how large predators survive in some of the most remote and unexplored ecosystems on Earth.

Unlikely Discovery: A Deep-Sea Predator in Unfamiliar Waters

Historically, the predator in question has been associated with cold, deep waters in the northern Pacific, ranging from Japan and the Bering Sea to Alaska and Baja California. The creature’s sudden appearance in the South China Sea, an area far warmer and more tropical than its typical habitat, has raised intriguing questions among marine scientists about its migration patterns and the factors influencing its range. Could shifting ocean temperatures be pushing the predator southward? Or could the abundant food sources in this region be the driving force behind its uncharacteristic journey?

The footage was captured using baited cameras, which were intended to attract scavengers to the ocean floor. What the team didn’t expect was the appearance of this deep-sea predator, which has now provided the first clear visual evidence of its behaviors in tropical waters.

Size and Feeding Behavior: A Hierarchy of Survival

The research team reviewed hours of footage and categorized the predator based on size. They found that individuals longer than 8.85 feet (2.7 meters) exhibited distinct feeding behaviors compared to their smaller counterparts. Larger individuals charged the carcass head-on, tearing large chunks of flesh, while the smaller individuals waited on the periphery, only venturing in after the larger predators had moved away. This suggests that size plays a critical role in access to food, with larger individuals commanding priority in the feeding hierarchy.

“This behavior suggests that feeding priority is determined by individual competitive intensity, even in deep-water environments,” said study author Han Tian, a marine biologist at Sun Yat-sen University. The larger individuals, due to their size, dominate the feeding process, leaving the smaller individuals to make do with whatever remains. This hierarchical feeding behavior reflects an organized system for sharing scarce resources in the deep ocean.

“This reflects a survival strategy suitable for non-solitary foraging among this deep-sea predator,” Tian added. The behavior underscores a sophisticated survival mechanism that likely plays a role in helping these predators survive in the competitive and food-limited conditions of the deep ocean.

Surprising Social Etiquette: Underwater Turn-Taking

One of the most surprising aspects of the footage was the predator’s behavior around the carcass. Unlike many scavengers that compete aggressively for food, the predator in question exhibited a surprisingly polite manner, taking turns with others. Once a predator had finished feeding, it would drift away, creating space for the next predator to approach. This orderly, almost respectful behavior suggests that these predators may follow a social system that helps reduce conflict, even in the competitive, resource-scarce environment of the deep sea.

The researchers were amazed to see such social structure in a predator that is typically seen as solitary. “This behavior suggests that feeding priority is determined by individual competitive intensity, even in deep-water environments,” Tian noted, indicating that the predator’s survival strategy might be based on non-solitary foraging, in which predators take turns instead of directly battling for food. Such behaviors, previously associated with surface-level scavengers, could play an important role in ensuring the predator’s survival in the deep-sea abyss, where food is sparse, and encounters with others are infrequent.

Eye Retraction: A Defense Mechanism for Feeding Frenzies

Another notable discovery from the footage is the predator’s eye retraction behavior. Unlike many other predators, this species lacks the nictitating membrane (a transparent eyelid) found in other sharks. Instead, the footage shows the predator retracting its eyes during feeding. Scientists believe this may be a protective measure against injury during the feeding frenzy, as the predator could be at risk of injury from protruding bones or the teeth of rival predators.

This eye retraction serves as an alternative to the missing membrane, helping the predator maintain its vision during chaotic feeding times. Such adaptations are crucial for survival in the unpredictable and often violent environment of the deep ocean, where every meal is a hard-fought battle.

The Mystery of the South China Sea’s Deep Ecosystem

The sudden appearance of this deep-sea predator in the South China Sea opens new questions about the region’s deep-sea ecosystem. Traditionally, such predators are known to scavenge on seals, squids, and other cold-water species in more temperate or polar waters. But in the subtropical South China Sea, the predator’s presence suggests that there may still be abundant nutrient pathways linking surface ecosystems to the deep ocean, providing sufficient food sources to support large predators in this region.

“The highly aggressive behavior of sharks observed in the South China Sea suggests that this region still harbors abundant food sources in the deep sea,” said Tan, another study author. “But what exactly are they? This question is intriguing for both animal distribution and behavioral research.” The team is now investigating what resources are available in these deep waters, and whether they are sufficient to sustain the predator over the long term.

The researchers plan to deploy additional baited cameras and environmental DNA samplers to further study the predator’s habits and determine if it is present year-round. Such studies will be critical in understanding how climate change and altered ocean currents may be affecting the distribution of cold-water species, and whether this predator’s migration to warmer waters is part of a larger trend.