Fish
Tube-eye
Stylephorus chordatus · also called thread-tail
Feeding not by biting or filtering but by suddenly ballooning its mouth into a tiny suction bubble, a tube-eye watches the water above with permanently upward-fixed, tubular eyes, one of the deep sea’s most distinctive and least conventional feeders.
Overview
The tube-eye, Stylephorus chordatus, is a small, delicately built deep-sea fish native to deep ocean habitat recorded across every major ocean basin. Its fixed, upward-pointing tubular eyes, highly unusual pipette-like feeding method, and distant kinship with the oarfish make it one of the more distinctive and unusual fish species found anywhere in the deep sea.
A feeding method almost unheard of among fish
Rather than lunging, biting, or filtering, the tube-eye relies on an extraordinary trick: expanding a small chamber in front of its mouth into a sudden bubble that sucks in prey almost like a pipette, a feeding style shared by almost no other fish species.
Status
Least Concern, though population trends remain largely unknown given the difficulty of surveying its deep-sea habitat.
Tube-eye: common questions
How does the tube-eye catch its food?
This species feeds by suddenly expanding a small chamber in front of its mouth into a bubble, creating suction that draws in prey in a manner unlike the feeding method of almost any other fish.
Why does the tube-eye have upward-pointing eyes?
This species has distinctive tubular eyes fixed permanently in an upward-pointing position, used to spot the silhouettes of small prey against the faint light filtering down from above.
Is the tube-eye related to the oarfish?
Yes, this species belongs to the same broader order as the oarfish, one of the ocean's longest bony fish, despite the two species looking very different from one another overall.
Why is it sometimes called the thread-tail?
This species has an unusually long, thread-like tail fin, a feature distinctive enough to give rise to one of its alternative common names.