When exploring in the ocean deep it’s not uncommon to come across some pretty alien-like lifeforms, but every now and then scientists stumble across something truly exceptional. Such an observation was recently made by researchers at the Monterey Bay Aquarium Research Institute (MBARI) who captured on camera something they’ve only seen four times in more than three decades of deep-sea research: a highfin dragonfish.
The exceptionally rare fish was spotted by Senior Scientist at MBARI Bruce Robison and colleagues who were on board the research vessel Western Flyer. Known as the highfin dragonfish (Bathophilus flemingi), it was shimmering through California’s waters at a depth of around 300 meters (980 feet) just outside of Monterey Bay.
The metallic fish looks “like a tiny bronze submarine,” commented one person on YouTube, or — as IFLScience's Managing Editor, Katy Evans, described it — a “deep-sea Toblerone”. However, when not on camera in its natural environment it likely looks very different.
“These fish live in either dim light or total darkness; the latter illuminated only by bioluminescence,” Robison told IFLScience. “So, their appearance in their natural habitat is nothing like what we see in these videos.”
“Many other fishes have silvery sides that reflect ambient light to help them blend into their surroundings visually. The metallic character of Bathophilus' skin probably has a similar function. As for color, there is variety among the specimens I have encountered. Some were bronze like this one; others were copper, or brass, or even metallic green. They may be able to adjust the color to suit the circumstances, or maybe not, we just don't know yet.”
While its orientation might look a little peculiar, this is part of dragonfishes' predation technique, which sees them hang motionless in the water until prey strays within reach. They then snap up whatever unlucky animal came within chomping distance with their large, toothy jaws.
Much mystery remains around Bathophilus owing to its elusive nature, but we do know it shares the water column with a rich diversity of species including squids, crustaceans, and worms, as well as some predatory marine mammals. “Anything bigger than this fish is a potential predator,” Robison explained. “It's a dangerous world for them.”
The team hopes this rare snippet of footage will contribute to our understanding of highfin dragonfish, being incorporated into a variety of ongoing studies exploring topics including (but not limited to) prey attraction behavior, the behavioral pigmentation pattern changes of deep-sea fishes, as well as the impact of climate change on marine communities at this depth.
“You never know how a chance observation like this will pay off,” said Robison, “but they usually do.”