There was much excitement among marine biologists at the Monterey Bay Aquarium Research Institute (MBARI) earlier this month when one of the team's remotely operated vehicles captured footage of an extremely rare deep-sea fish.

The highfin dragonfish, or Bathophilus flemingi if you prefer, was seen swimming around 300 metres (980 feet) below the surface of the ocean off the coast of northern California. This striking fish has a distinct torpedo shape and an almost metallic bronze glow that intensifies under white light. Long, wing-like filaments act as fins and are believed to pick up vibrations that aid the fish when hunting or avoiding predators.

"In more than three decades of deep-sea research and more than 27,600 hours of video, we’ve only seen this particular species four times!" the team wrote online.

The video, which was uploaded on MBARI’s YouTube channel, shows the fish swimming downward against the dark blue backdrop of the deep-sea. Amazed viewers commented on its unique appearance, describing it as  "a tiny bronze submarine" and "nature’s torpedo".

Similar to many other deep-sea creatures, the dragonfish uses bioluminescence to attract prey in the darkest depths. Despite this individual’s vibrant appearance under white light, dragonfish are generally black in colour with reports of some sporting the darkest pigments known to exist in the natural world. This allows them to become almost invisible to predators and unsuspecting prey as they float motionless, waiting to snap up passing crustaceans and fish.

MBARI researchers described the recent sighting as one of the rarest they have encountered in Monterey Bay. Discoveries such as these provide researchers with valuable new material that enables them to learn more about the mysterious creatures that lurk in the depths of our oceans.

Header image: MBARI