Bony fish · Argentiniformes · Opisthoproctidae

Barreleye

Macropinna microstoma

Not Evaluated

It has not yet been assessed against the IUCN criteria. See full glossary

Macropinna microstoma, known in Spanish as pez cabeza transparente and sometimes as pez duende, is the only fish species of the genus Macropinna, belonging to the family Opisthoproctidae. It is recognisable by its transparent head, in contrast with the opacity of the rest of the body. It lives between 600 and 800 metres deep.

Size

10 cm – 15 cm

Diet

Carnivore

Feeds mainly on other animals.

Social structure

Solitary

Lives and hunts alone, joining others only to breed.

Sighting difficulty

Unknown

OceanCarnivore Solitary Fish Ocean

5countries

Fun facts

GeneralIts head is a transparent dome, and its tubular eyes look upward from inside it.
For decades the existence of the dome went unknown, because it always broke as specimens were hauled up in the nets, and it was not documented intact until 2009.
Its tubular eyes can rotate from looking upwards to looking forwards, which lets it track prey right into its mouth.
The two dark spots above its mouth that look like eyes are in fact olfactory organs.
Its green tubular eyes sit inside a transparent, fluid-filled dome covering its head; what look like eyes from outside are in fact the nostrils.
For seventy years it was believed it could only look upwards: in 2009 MBARI showed with submersibles that it rotates its eyes forward to feed.
It is thought to position itself beneath the tentacles of siphonophores and steal the prey caught there; the transparent dome would protect it from the stinging cells.