Giant sea spiders found transporting crustaceans in the Pacific

Marine biologists exploring the southeastern Pacific Ocean near the Chilean margin have discovered a unique symbiotic behavior involving giant sea spiders and shrimp-like crustaceans. Using the robotic submersible SuBastian, researchers observed amphipods of the species Mespleustes abyssorum hitchhiking on the bodies of Colossendeis colossea, the largest known species of sea spider.

The observations occurred at depths of approximately 3,000 meters. The team recorded a sea spider with at least three amphipod passengers in November 2024, and encountered another similar pairing roughly 225 kilometers away four days later.

According to a study published in the journal Ecology, these findings highlight the importance of direct in situ exploration in uncovering hidden ecological interactions within remote and unexplored deep-sea ecosystems.