How does a barreleye fish eat?

The barreleye fish (Macropinna microstoma) has a unique and fascinating feeding strategy. Here's how it eats:

1. Locating Prey:

* Transparent Dome: The barreleye's most striking feature is its transparent dome-shaped head, which houses its tubular eyes.

* Upward-Facing Eyes: The eyes are not fixed in place but can rotate within the dome, allowing the fish to look upward.

* Detecting Bioluminescence: The barreleye is thought to use its sensitive eyes to detect the bioluminescent light emitted by jellyfish and other prey organisms.

2. Targeting and Capturing:

* Vertical Movement: The barreleye typically swims upside down, allowing its eyes to scan the water column for prey.

* Rapid Maneuvers: Once prey is located, the barreleye uses its pectoral fins to maneuver quickly and capture it with its small, toothless mouth.

* Prey Selection: The barreleye mainly feeds on small crustaceans, siphonophores, and other gelatinous zooplankton.

3. Ingesting Prey:

* Small Mouth: Its small mouth may not be able to accommodate large prey, so it likely prefers smaller organisms.

* Mouth Orientation: The mouth is located beneath the head, allowing the barreleye to easily grab prey and pull it in.

Overall, the barreleye fish's unique anatomy and behavior have evolved to allow it to effectively hunt in the dim depths of the ocean, where bioluminescent light is the key to finding food.