Deepest decapod

In October 2008, a baited video lander was deployed in the Japan Trench located in the Pacific Ocean north-east of Japan as part of a study to examine whether any decapod resides within the ocean's hadal zone (6,000 metres/19,685 feet or below). During the survey, a solitary Benthesicymid prawn (Benthesicymus crenatus) was recorded on camera at a depth of 7,703 metres (25,272 feet), the deepest that any decapod crustacean has been sighted in situ to date. The findings of the research were published in the journal Deep-Sea Research on 17 November 2008.

As part of the study, the same species of prawn was also sighted 5,469 m (17,943 ft) in the region of the Mariana Trench and down to 6,890 m (22,605 ft) in the Kermadec Trench; the latter two submarine trenches are located in the South Pacific, whereas the Japan Trench sits above the equator in the North Pacific.

On earlier dives conducted in late 2007, a total of 29 sightings of Benthesycimid prawns (20 individuals) were made at 6,945 m (22,785 ft) in the Japan Trench.

During exploration of the Kermadec Trench, another decapod was also recorded at up to 6,890 m (22,605 ft): Caridean prawns. Their small size did not make it possible to identify them other than that they are from the Acanthephyra genus. In any case, they were not seen beyond this depth, so the Benthesycimid prawn remains the outright record holder based on sightings to date.

The paper was a collaboration between the University of Aberdeen, UK, and the University of Tokyo, Japan, led by Dr Alan Jamieson and Dr Toyonobu Fujii.