This article originally appeared in the February 2021 issue of the Deep-sea Mining Observer. It is reprinted here with permission. For the latest news and analysis about the development of the deep-sea mining industry, subscribe to DSM Observer here: http://dsmobserver.com/subscribe/

Even with the intense research focus of the last twenty years, the deep sea is still almost entirely unexplored. New species are par for the course every time a fresh sample is recovered from the abyssal plain. The vast biodiversity of the deep seafloor is offset by a biomass deficit; the denizens of the deep sea, with a few notable exceptions, are few and far between, their size often limited by the paucity of food available to them. While giants like the Japanese King Crab or the Giant Deep-sea Isopod do occur, the vast majority of deep-sea species are relatively small. 

The discovery of new species in the deep ocean is common, but the discovery of new giants in the deep sea is extremely rare. 

Last month, a research team from the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) led by Dr. Yoshihiro Fujiwara and the Deep-sea Biodiversity Research Group announced the discovery of a new species of slickhead from the deep waters around Suruga Bay. Weighing in at 25 kilograms and measuring 140 centimeters, the Colossal Slickhead, described from four specimens recovered from depths greater than 2000 meters, is the largest species of slickhead (a group of deep-sea fishes found in waters deeper than 1,000 meters) yet described. 

In Japan, slickheads are commonly called sekitori iwashi–’massive sardines’. In recognition of its immense size, the researchers gave this most massive of massive sardines the common name yokozuna iwashi, after the title given to champion sumo wrestlers. 

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