Bean's bigscale

About bean's bigscale

Bean’s bigscale could be the poster child for why we need to study the ocean twilight zone. Though it has been pulled up in deep-sea trawls from across the Atlantic Ocean as well as the subtropical Indian and Pacific oceans, very little is known about this bigscale or “ridgehead” fish. This knowledge gap could be due to the fact that it lives so deep (800 – 4,000 meters or 2,600 – 13,000 feet) and isn’t particularly abundant. But maybe it’s because the Bean's bigscale is on the hideous side. Like the fangtooth, its black body—particularly its head—is pitted with mucous-filled cavities. When pulled up in trawl nets, the fish tend to lose their large scales, revealing open pockets of slime.

Yuck factor aside, studying these fish can illuminate important processes in the mid-ocean. A 2014 study of live-captured bean’s bigscale behavior revealed that the fish swim with a powerful and highly maneuverable “rowing” motion, which the researchers found surprising because of the amount of energy it takes to move this way. Considering that Bean’s bigscales tend to hang out around continental slopes, where upwelling nutrients attract crowds of zooplankton, the researchers concluded that this strategy pays off for feeding in dense swarms. The stomachs of dissected specimens have been found full of gelatinous salps, with the occasional dash of copepods, ostracods, euphausiids and small fish.