Twelve hundred fathoms down, where the weight of the sea tightens to something like a hundred atmospheres, there is no stray photon from the surface. The water is colder than the melt of a glacier and blacker than the interstice between stars. I have observed this phenomenon across three descents in the Porcupine Abyssal Plain, and I am prepared to state that the light is bacterial in origin and entirely unaccounted for in the existing literature on marine luminosity.
The Symbiont Hypothesis
When I dissected the first specimen aboard H.M.S. Challenger in the spring of ’74, the esca tissue proved a dense colony of rod-shaped bacteria. The light persists for hours after the host’s death — a fact which settles the question of its origin. These are not mere phosphorescent secretions but a living culture, passed from one generation of fish to the next through a mechanism we have yet to observe.
The ceratioid does not burn its own fuel. It borrows the light of another kingdom entirely.
I am now cataloguing seventeen distinct morphologies of the esca — some barbed, some fringed, one shaped like a minute lantern with a shutter of pigmented skin — each a different evolutionary answer to the problem of being seen in a place that has never known seeing.