1000–4000 m

Bathypelagic zone

No sunlight ever reaches this deep. The only light is produced by the organisms themselves.

Light: Total darkness
Temperature: 2–4°C
Pressure: 100–400 atm
Anguille pélican et sa bouche démesurée
Harmless

Pelican eel

Eurypharynx pelecanoides

Pelican eel

Equipped with an oversized mouth able to stretch to swallow prey far larger than itself, it compensates for poor eyesight with a bioluminescent tail used as a lure.

🌊 5003000 m

  • Can swallow prey far larger than itself thanks to an extensible stomach
  • Has a light organ at the tip of its tail used as a lure
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Baudroie abyssale et son leurre bioluminescent
Harmless

Humpback anglerfish

Melanocetus johnsonii

Humpback anglerfish

Hunts in total darkness using a bioluminescent lure dangling above its mouth, and practises one of the strangest reproductive strategies in the animal kingdom: the tiny male ends up fusing with the female.

🌊 3001200 m

  • Fishes with a bioluminescent lure produced by symbiotic bacteria
  • Extreme sexual parasitism: the male fuses physically and vascularly with the female
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Cachalot femelle et son petit
Low danger

Sperm whale

Physeter macrocephalus

Sperm whale

The unwitting hero of the novel Moby-Dick and centuries of sailors' legends of titanic battles against monsters of the deep, the sperm whale does indeed fight real duels with the giant squid, whose sucker scars it often carries on its skin.

🌊 02000 m

  • Often carries sucker scars on its skin left by battles with giant squid
  • Among the deepest divers of all marine mammals, beyond 2,000 m, on a single breath for over an hour
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Calmar de Humboldt
Moderate danger

Humboldt squid

Dosidicus gigas

Humboldt squid

Nicknamed the "red devil" for its shifting colour and aggression during group hunts, it can hunt in shoals of several hundred and communicates by rapidly changing colour.

🌊 01200 m

  • Changes colour in a fraction of a second, probably to coordinate group hunting
  • Tolerates extremely oxygen-poor zones inaccessible to most of its predators
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Illustration scientifique du calmar vampire
Harmless

Vampire squid

Vampyroteuthis infernalis

Vampire squid

Despite its terrifying name, "vampire squid from hell", it is a peaceful creature that doesn't hunt but instead filters organic debris drifting in total darkness.

🌊 6001200 m

  • Releases a cloud of bioluminescent mucus instead of ink to escape predators
  • Can turn its membrane inside out like a cape bristling with false spines
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Crabe yeti près d'une source hydrothermale (campagne Ifremer)
Harmless

Yeti crab

Kiwa hirsuta

Yeti crab

Discovered only in 2005 near Easter Island, this deep-sea crab literally farms bacteria on its hairy claws to feed on them.

🌊 15002500 m

  • Literally farms bacteria on its own claws to feed on them
  • Can form extremely dense aggregations, several hundred individuals per square metre
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Grand requin blanc en pleine nage
High danger

Great white shark

Carcharodon carcharias

Great white shark

An iconic apex predator able to leap clean out of the water to surprise prey, and to cover thousands of kilometres on transoceanic migrations still poorly understood.

🌊 01200 m

  • Can leap entirely out of the water to surprise prey at the surface
  • Ultra-fine electroreception via hundreds of ampullae of Lorenzini
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Pieuvre Dumbo et ses nageoires en forme d'oreilles
Harmless

Dumbo octopus

Grimpoteuthis sp.

Dumbo octopus

The cephalopod observed at the greatest depths ever recorded: it owes its name to its two ear-shaped fins reminiscent of the Disney elephant.

🌊 10007000 m

  • The cephalopod observed at the greatest depths ever recorded, down to about 7,000 m
  • Swims by flapping two ear-shaped fins, a technique unique among octopuses
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Poulpe géant du Pacifique
Harmless

Giant Pacific octopus

Enteroctopus dofleini

Giant Pacific octopus

Long feared as the "devilfish" in the legends of Indigenous peoples of the North American Pacific coast, this largest known octopus in the world turns out to be remarkably intelligent, able to open jars and recognise individual humans.

🌊 01500 m

  • Has nine brains, one central and one in each of its eight arms, able to act almost independently
  • Intelligence documented in the lab: able to open jars and recognise certain individual humans
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Requin à collerette, silhouette serpentiforme caractéristique
Low danger

Frilled shark

Chlamydoselachus anguineus

Frilled shark

Nicknamed the "snake shark" or a living fossil, it has changed very little in 80 million years and resembles a giant eel with 300 needle-like teeth.

🌊 501500 m

  • Considered a living fossil, virtually unchanged for 80 million years
  • The longest known gestation period of any vertebrate: about 3.5 years
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Requin-baleine et plongeurs, mer d'Andaman
Harmless

Whale shark

Rhincodon typus

Whale shark

The largest fish in the world, a peaceful filter feeder that can reach the size of a school bus while feeding almost exclusively on plankton.

🌊 01900 m

  • The largest fish in the world, able to exceed 18 metres in length
  • A spot pattern unique to each individual, like a fingerprint
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Requin-lutin et son museau caractéristique
Low danger

Goblin shark

Mitsukurina owstoni

Goblin shark

Nicknamed the "alien shark", it projects its jaws out of its head at blinding speed to catch prey — one of the strangest attacks in the animal kingdom.

🌊 1001300 m

  • Can project its jaws out of its head in a fraction of a second to catch prey
  • Detects prey via electrical sensors spread across its long snout
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Tortue luth sur une plage des Îles Vierges
Harmless

Leatherback turtle

Dermochelys coriacea

Leatherback turtle

The largest sea turtle and the deepest-diving reptile known, able to keep its body warmer than the icy deep water thanks to a unique soft, cartilaginous shell.

🌊 01280 m

  • The deepest-diving reptile known, beyond 1,000 m
  • Can keep its body warmer than the icy water thanks to a unique vascular system
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Colonie de vers tubicoles géants près d'une source hydrothermale (campagne Ifremer)
Harmless

Giant tube worm

Riftia pachyptila

Giant tube worm

Lacking a mouth, stomach or anus, it lives entirely thanks to symbiotic bacteria that convert the toxic hydrogen sulfide of hydrothermal plumes into energy.

🌊 15002500 m

  • Lives without a mouth or stomach, entirely nourished by internal symbiotic bacteria
  • Its hemoglobin carries both oxygen and a deadly poison without harm, a unique biochemical feat
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