How We Know

Creature reference

Colossal squid

Mesonychoteuthis hamiltoni · 500–2,200 m

Reference answer

The heaviest known invertebrate, with enormous eyes and rotating hooks on the tentacle clubs.

Adaptations

  1. Very large light-collecting eyes
  2. Rotating tentacle hooks
  3. Cold-water Southern Ocean physiology

Depth zones

Twilight ZoneA dim global layer where enormous numbers of animals migrate upward at night and descend before dawn.Midnight ZoneThe largest continuously dark habitat, where food is scarce and animals rely on specialized senses, lures and low-energy strategies.

Evidence

Sources reviewed

  1. Colossal squidMuseum of New Zealand Te Papa Tongarewa · checked 2026-07-30
  2. The eyes of the colossal squidMuseum of New Zealand Te Papa Tongarewa · checked 2026-07-30