In a groundbreaking study published on June 1, 2025, in the journal *Ocean-Land-Atmosphere Research*, scientists have unveiled the intricate behaviors of the Pacific sleeper shark (*Somniosus pacificus*) in the South China Sea. This discovery, made southeast of Hainan Island, marks the first documented presence of this species in the region, challenging previous assumptions about their geographical range.
Researchers deployed a cow carcass at a depth of 1,629 meters, simulating a "whale fall" environment to observe the sharks. The footage revealed a complex social structure, with sharks exhibiting feeding hierarchies and queuing behavior. Larger sharks displayed aggressive feeding strategies, while smaller ones adopted a more cautious approach, potentially indicating age or size-related roles in the scavenging community.
The study also highlighted a unique physiological adaptation: eye retraction movements during feeding, likely to protect their vision. The presence of only female sharks suggests the South China Sea could be a crucial nursery or reproductive ground. This research, a collaboration between Chinese institutions, underscores the need for further exploration to understand deep-sea ecosystems and the impact of environmental changes.