Have you heard of dark matter? Here's how the Encyclopedia Britannica defines it:
[...] a component of the universe whose presence is discerned from its gravitational attraction rather than its luminosity. Dark matter makes up 30.1 percent of the matter-energy composition of the universe; the rest is dark energy (69.4 percent) and “ordinary” visible matter (0.5 percent).
So most of the universe is dark matter. Here's the mind-blowing biological equivalent: 95% of all of the biomass of fish lie in the mesopelagic zone of the ocean, thousands of feet below the surface of the water and shrouded in perpetual darkness. Phys.org explains:
UWA Professor Carlos Duarte says mesopelagic fish – fish that live between 100 and 1000m below the surface – must therefore constitute 95 per cent of the world's fish biomass. [...]
Prof Duarte led a seven-month circumnavigation of the globe in the Spanish research vessel Hesperides, with a team of scientists collecting echo-soundings of mesopelagic fish.
He says most mesopelagic species tend to feed near the surface at night, and move to deeper layers in the daytime to avoid birds.
They have large eyes to see in the dim light, and also enhanced pressure-sensitivity.
"They are able to detect nets from at least five metres and avoid them," he says.
Prof. Duarte and his colleagues were able to use acoustic techniques to to reliably detect the fish.
-via Kottke | Image: Daniel Mietchen