This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: During a recent expedition aboard the research vessel David Packard, MBARI scientists encountered a rarely seen barreleye fish (Macropinna microstoma). This sighting is MBARI's 11th observation of this unique deep-sea fish with a transparent head.
Researchers from MBARI's Biodiversity and Biooptics Team were exploring waters approximately 90 kilometers (55 miles) offshore, filming and collecting deep-sea animals with the remotely operated vehicle (ROV) Doc Ricketts when they happened upon a barreleye fish approximately 600 meters (1,970 feet) underwater. "Seeing a barreleye fish is a rare treat. Crew from across the ship joined the science team in the control room, mesmerized by this remarkable animal.
Deep-sea animals capture the imagination, creating wonder and awe that we hope will inspire stewardship of the largest living space on Earth," said senior scientist Steven Haddock. During the eight-day Diving Deep for Delicate Drifters expedition, Haddock and team set out to study gelatinous animals like jellies, siphonophores and ctenophores. Combining blue-water scuba diving near the surface with ROV surveys hundreds of meters underwater, this expedition supported the team's ongoing work to understand how gelatinous animals have adapted to life in the deep water column.
With science operations complete for the day, MBARI's submersible pilots were "flying" ROV Doc Ricketts back to the surface for recovery when research specialist Shannon Johnson spotted the barreleye and called out for them to stop. Most of the science team had relocated to the ship's wet lab to prepare to catalog the incoming specimens from the ROV and ran back to the control room, joined by the ship's crew, when they heard the news. The sighting of a barreleye fish was an exhilarating surprise capping off a long and productive week of deep-sea research.
Past MBARI observations by senior scientist Bruce Robison and research specialist Kim Reisenbichler were instrumental in revealing this fish's unique feeding behavior. Macropinna lives in the ocean's twilight zone, scanning the waters above for the silhouettes of prey. Large fins provide stability and maneuverability as a barreleye drifts in place, eyes transfixed on the waters above.
After spotting a tasty morsel, those large tubular eyes rotate beneath a dome of transparent tissue to keep prey in sight. The gelatinous shield also protects the fish's eyes when plucking small crustaceans caught in the stinging tentacles of deep-sea siphonophores. The expedition team spent approximately 20 minutes observing the barreleye, leveraging a high-resolution 4K camera on ROV Doc Ricketts to get a closer look at the animal's body and behavior.
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