Mysteries of the Twilight Zone | Worlds of the Deep

Natural World Facts2 minutes read

The deep sea is a diverse ecosystem with unique challenges and adaptations, including chemosynthetic oases and migration cycles. Various creatures in the Twilight Zone have evolved camouflage methods and unique features to survive in the dark depths, contributing to the overall biodiversity and productivity of the ocean.

Insights

  • The deep sea, once thought to be devoid of life according to Edward Forbes' abyssus theory, is now known to be teeming with biodiversity, supported by chemosynthetic oases at hydrothermal vents.
  • The vertical migration of creatures in the Twilight Zone, including unique gelatinous zooplankton and predatory Red Devil squid, plays a crucial role in the deep sea ecosystem by sequestering carbon, providing food for deeper communities, and shaping biodiversity in the challenging midnight zone.

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Recent questions

  • What is the deep sea like?

    Mysterious, dark, and home to unique creatures.

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Summary

00:00

Exploring the Rich Biodiversity of the Deep Sea

  • The deep sea is a world of Silence, emptiness, and darkness, where life exists in a formless void.
  • Edward Forbes' abyssus theory from 1843 suggested marine life decreases with depth, but we now know the deep sea is rich in biodiversity.
  • Chemosynthetic oases at hydrothermal vents support life in the deep sea by converting hydrocarbons into food.
  • The deep sea is divided into chemosynthetic and non-chemosynthetic regions, each with unique challenges and adaptations.
  • The mid-water zone in the deep sea is a vast ecosystem with unique creatures adapted to survive in different zones based on depth and light levels.
  • The Schmidt Ocean Institute's research vessel, RV Falkor II, has been exploring the deep sea since 2009, shedding light on its wonders.
  • The epipelagic zone, or sunlight zone, is home to more than 90% of marine life, supported by phytoplankton through photosynthesis.
  • The Twilight Zone, or mesopelagic, below the epipelagic lacks sunlight for photosynthesis, with marine snow providing the main food source.
  • Unique creatures in the Twilight Zone include gelatinous zooplankton, like the gossamer worm and the bloody belly cone jelly.
  • Camouflage methods in the deep sea include counter shading, bioluminescence, transparency, and silvering, used by various species to blend in with their environment.

26:21

Oceanic Vertical Migration: A Vital Ecosystem Process

  • Cephalopods use proteins called reflectins to create a mirror-like effect for counter-illumination, with the cockeyed squid having one large eye looking up and a small eye looking down to spot bioluminescence in the deep sea.
  • Creatures in the Twilight Zone migrate vertically every night, with vast numbers of animals rising from the mesopelagic depths to feed near the surface, forming the largest synchronous migration on Earth.
  • Lantern fish, crucial for marine food webs, are preyed upon by Red Devil squid that engage in cannibalism when food runs out, growing rapidly and reaching over a meter in length in less than a year.
  • The vertical migration cycle plays a vital role in the ocean's productivity, sequestering carbon, providing food for deeper communities, and shaping biodiversity, especially in the stable but challenging midnight zone below a thousand meters.
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