What lies in the ocean's twilight zone

Each animal in the ocean has its own auditory signature that ships detect by sending out sound waves that bounce off their bodies. But the acoustic fingerprints of twilight zone animals are mysterious because sonar does not have the bandwidth to dist
Each animal in the ocean has its own auditory signature that ships detect by sending out sound waves that bounce off their bodies. But the acoustic fingerprints of twilight zone animals are mysterious because sonar does not have the bandwidth to distinguish the organisms living far below the surface in an area so dense with life that people once thought it was the sea floor. Around 250 species of myctophids, or lantern fish (above), make up much of this dense layer. Though abundant enough to trick sonar, individually they are no bigger than your index finger.PHOTOS: WOODS HOLE OCEANOGRAPHIC INSTITUTE
Instead of squirting ink to escape predators, the fist-size glass squid (far left) hides in plain sight, pulling its tentacles and head inside its spike-covered body cavity. Then it fills this squid orb with its own ink. The fang-toothed monster (lef
The fang-toothed monster (above) has one of the biggest teeth-to-body-size ratios in the animal kingdom. Its teeth are too large for its mouth to accommodate, so it just closes them like a cage, imprisoning its prey.
Each animal in the ocean has its own auditory signature that ships detect by sending out sound waves that bounce off their bodies. But the acoustic fingerprints of twilight zone animals are mysterious because sonar does not have the bandwidth to dist
Instead of squirting ink to escape predators, the fist-size glass squid (above) hides in plain sight, pulling its tentacles and head inside its spike-covered body cavity. Then it fills this squid orb with its own ink. PHOTOS: WOODS HOLE OCEANOGRAPHIC INSTITUTE

Scientists using new tech to better understand strange denizens of the deep - and create an auditory dictionary

Between the ocean's bright blue surface and its blackest depths - 200m to 1km below - is a mysterious, dark span of water. Welcome to the twilight zone.

Recent evidence suggests there are more animals in this zone by weight than in all of the world's fisheries combined. But who lives in the area, and in what quantities?

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A version of this article appeared in the print edition of The Straits Times on November 24, 2018, with the headline 'What lies in the ocean's twilight zone'. Print Edition | Subscribe