Researchers have been exploring Earth’s oceans for centuries, and advances in submersible technology continue to unveil new and fascinating discoveries.
While many deep‑sea species have been documented, the Pacific sleeper shark—an enormous predator that typically inhabits the colder, deeper waters of the northern Pacific—remained elusive in the South China Sea. To investigate feeding strategies of large deep‑sea animals, a research team sank a cow carcass to a depth of 5,344 feet on the continental slope southeast of Hainan Island.
Surprisingly, the carcass attracted eight Pacific sleeper sharks, a first for this region and the first documented sighting of the species this far south. The study, published in Ocean–Land–Atmosphere Research, expands the known range of this shark beyond its usual temperate habitats.
In footage released on YouTube, the sharks displayed remarkable queuing behavior. Larger individuals—over nine feet long—aggressively tore into the carcass, while smaller sharks circled the feeding area more cautiously. Notably, the sharks appeared to yield their spots to those approaching from behind, suggesting a nuanced feeding hierarchy.
Han Tian, lead author of the study, explained that "this behavior indicates that feeding priority is determined by individual competitive intensity, even in deep‑water environments, reflecting a survival strategy suitable for non‑solitary foraging among Pacific sleeper sharks."
During feeding, the sharks also exhibited eye retraction, a defensive adaptation likely compensating for the lack of a nictitating membrane. The fact that all eight sharks observed were female hints that the South China Sea could serve as a nursery, mirroring patterns seen in other large deep‑sea species in the region.
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