Barreleye Identification Guide

Key identification features

• Transparent, fluid-filled dome covering the top of the head
• Tubular, telescoping eyes visible through the transparent shield, typically directed upward but able to rotate forward
• Small, weak mouth relative to head size
• Large, broad pectoral fins used for hovering and fine positional control
• Flattened fins and a somewhat torpedo-shaped, dark to silvery body
• Modest size, generally 4-6 inches long
• Two small, forward-facing nostril-like structures sit in front of the eyes atop the transparent shield

Common look-alikes

• Hatchetfish: also has upward-directed eyes but lacks any transparent dome and has a strongly compressed, hatchet-shaped body
• Telescopefish: eyes protrude externally on stalks rather than being enclosed within a transparent, fluid-filled shield
• Lanternfish: normal, non-tubular eyes and no transparent head structure, easily separating it from barreleye

Where you'll see one

Barreleyes live in the deep mesopelagic zone, typically between 600 and 2,600 feet, in oceans worldwide. They hover nearly motionless in the water column, using their upward-pointing eyes to spot the silhouettes of prey or faint bioluminescent flashes above them in the near-total darkness.