This footage of a magnificent barreleye (aka "spook fish") was captured by the Monterey Bay Aquarium Research Institute underwater robot off the coast of California. The barreleye (Macropinna microstoma) reaches a maximum size of 6 inches and lives at depths of around 2,500 feet. From MBRI:
Its eyes look upwards to spot its favorite prey—usually small crustaceans trapped in the tentacles of siphonophores—from the shadows they cast in the faint shimmer of sunlight from above. But how does this fish eat when its eyes point upward and its mouth points forward? MBARI researchers learned the barreleye can rotate its eyes beneath that dome of transparent tissue. Aquarist Tommy Knowles and his team were aboard MBARI's R/V Rachel Carson with our ROV Ventana to collect jellies and comb jellies for the Aquarium's upcoming Into the Deep exhibition when they spotted this fascinating fish. The team stopped to marvel at Macropinna before it swam away.