Scientists capture first-ever video of Winteria telescopa—a rare barreleye fish—in Atlantic’s Twilight Zone

A Rare Glimpse Into the Atlantic Doldrums

The Anatomy of the Twilight Zone

The fish was filmed within the mesopelagic region, or “twilight zone,” an area 600 to 1,000 meters below the surface where sunlight fades to a faint, mysterious glow. The Winteria telescopa is best known for its extraordinary transparent head, which houses its eyes internally. Because this delicate dome typically collapses when specimens are hauled to the surface in nets, scientists have historically been limited to studying damaged samples. Seeing the fish in situ provides a rare, unfiltered look at its behavior. Most members of this species are small, measuring roughly 10 to 15 centimeters—about the size of a banana.

Upward Vision as an Evolutionary Edge

Unlike most fish, whose eyes sit on the sides of their heads, the Winteria telescopa features eyes pointed directly upward. This specialized anatomy allows the fish to capture the weakest traces of light filtering from the surface. By peering toward the surface, the fish can detect the silhouettes of prey, such as squid and jellyfish, moving above it. Scientists believe these fish feed on available prey, occasionally snatching small portions trapped in the long, thread-like tentacles of siphonophores and other gelatinous organisms.

Uncovering Hidden Ecosystems

The filming of the Winteria telescopa was only one highlight of the July expedition. The team identified two previously unknown hydrothermal vent fields hidden within a fault zone. These vents release mineral-rich, hot fluids that sustain thriving ecosystems in the absence of sunlight. The researchers also encountered two specimens of the elusive “bigfin squid,” a deep-sea creature rarely seen, characterized by its exceptionally long, thread-like tentacles.

Mapping the Unknown

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