Scientists have discovered mysterious jet-black eggs in the depths of the Pacific Ocean, setting a new record for the deepest free-living flatworms ever observed.
The eggs were found by Dr Yasunori Kano from the University of Tokyo, who piloted a remote-operated vehicle (ROV) in the Kuril-Kamchatka Trench, at a staggering depth of 6,200 metres . He collected some samples and brought them to Dr Keiichi Kakui and Aoi Tsuyuki of Hokkaido University for further analysis.
The researchers were surprised to find that the eggs were actually flatworm egg capsules, each containing three to seven flatworms. They identified them as belonging to suborder Maricola in Tricladida, a group of marine flatworms that are usually found in shallow waters. This discovery established them as the deepest-dwelling free-living flatworms known on Earth .
The researchers also noted that the developmental patterns of these deep-sea flatworms were remarkably similar to those of their shallow-water counterparts, challenging previous assumptions about environmental adaptation . They speculated that these flatworms might have evolved some special adaptations to survive in the extreme conditions of the deep sea, such as high pressure, low temperature and limited light.
The study, published in the journal Biology Letters, highlighted the unprecedented nature of this discovery and its implications for understanding the diversity and evolution of marine flatworms. The researchers plan to continue their investigation of these enigmatic black eggs and the flatworms inside them, hoping to learn more about their life cycle and ecology.