200–1000 m
Mesopelagic zone
The twilight zone. Light fades rapidly and disappears entirely. This is where the first bioluminescent species appear.
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.
🌊 500–3000 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
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.
🌊 300–1200 m
- ⚡ Fishes with a bioluminescent lure produced by symbiotic bacteria
- ⚡ Extreme sexual parasitism: the male fuses physically and vascularly with the female
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.
🌊 0–2000 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
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.
🌊 0–1200 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
Giant squid
Architeuthis dux
Giant squid
The source of the Kraken myth for centuries, it is one of the largest invertebrate creatures known, never filmed alive in its natural habitat before 2004.
🌊 300–1000 m
- ⚡ The largest eyes in the animal kingdom (up to 27 cm in diameter)
- ⚡ Copper-based blue blood, adapted to carrying oxygen in cold, deep water
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.
🌊 600–1200 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
Coelacanth
Latimeria chalumnae
Coelacanth
Believed extinct for 65 million years, alongside the dinosaurs, until its spectacular rediscovery in 1938 off South Africa.
🌊 150–700 m
- ⚡ Believed extinct for 65 million years until its rediscovery in 1938
- ⚡ Fleshy fins that move like limbs, close to the ancestor of the first land vertebrates
Sea cucumber
Holothuria sp.
Sea cucumber
A true vacuum cleaner of the seafloor, continuously recycling sand and sediment — some species defend themselves by expelling their own internal organs at an attacker.
🌊 0–1000 m
- ⚡ Can expel its own internal organs to repel a predator, then regenerate them entirely
- ⚡ Recycles a considerable amount of marine sediment every year, an essential ecological role
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.
🌊 0–1200 m
- ⚡ Can leap entirely out of the water to surprise prey at the surface
- ⚡ Ultra-fine electroreception via hundreds of ampullae of Lorenzini
Narwhal
Monodon monoceros
Narwhal
Nicknamed "the unicorn of the sea", this Arctic whale carries a long spiralled tusk that long fuelled the unicorn myth in Europe.
🌊 0–800 m
- ⚡ Its spiralled tusk, actually a tooth, can exceed 2.5 metres in length
- ⚡ Dives up to 800 m on a single breath to hunt, one of the deepest dives known in a marine mammal
Chambered nautilus
Nautilus pompilius
Chambered nautilus
A true living fossil whose shape has barely changed in over 500 million years, it navigates using a chambered shell that works like a natural submarine.
🌊 0–700 m
- ⚡ A shape virtually unchanged for over 500 million years
- ⚡ Regulates its depth like a submarine, using a shell with gas-filled chambers
Orca
Orcinus orca
Orca
The largest dolphin in the world and such a sophisticated apex predator that some populations develop hunting techniques passed down culturally from generation to generation.
🌊 0–500 m
- ⚡ Develops hunting techniques unique to each population, passed down culturally
- ⚡ A distinct vocal repertoire per family group, a form of dialect
Leopard seal
Hydrurga leptonyx
Leopard seal
Antarctica's top predator after the orca, recognisable by its reptilian head and immense jaw, able to hunt both penguins and other seals.
🌊 0–300 m
- ⚡ Can both filter krill and hunt large prey such as a penguin or a young seal
- ⚡ One of the few seals known to actively prey on other seals
Lanternfish
Myctophum punctatum
Lanternfish
One of the most abundant fish in the ocean: every night it rises from the depths to feed near the surface, then dives back at dawn — a planet-wide daily migration.
🌊 10–700 m
- ⚡ Counter-illumination: its photophores mimic daylight to make it invisible from below
- ⚡ Undertakes one of the planet's largest animal migrations by biomass, every single day
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.
🌊 0–1500 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
Giant manta ray
Mobula birostris
Giant manta ray
The largest ray in the world, a peaceful filter feeder with a brain proportionally among the largest of all fish, able to recognise itself in a mirror in the laboratory.
🌊 0–1000 m
- ⚡ One of the few fish to pass a mirror self-recognition test in the laboratory
- ⚡ A brain proportionally among the largest of all fish
Giant oarfish
Regalecus glesne
Giant oarfish
In Japan it is nicknamed the "messenger from the palace of the dragon god", and its appearance near the coast is sometimes seen as an omen of an imminent earthquake — a legend science has never confirmed but which likely explains the origin of many sea-serpent tales.
🌊 20–1000 m
- ⚡ Can swim in a perfectly vertical, motionless position, rippling only its dorsal fin
- ⚡ Its rare, spectacular strandings have fuelled the sea-serpent legend for centuries
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.
🌊 50–1500 m
- ⚡ Considered a living fossil, virtually unchanged for 80 million years
- ⚡ The longest known gestation period of any vertebrate: about 3.5 years
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.
🌊 0–1900 m
- ⚡ The largest fish in the world, able to exceed 18 metres in length
- ⚡ A spot pattern unique to each individual, like a fingerprint
Megamouth shark
Megachasma pelagios
Megamouth shark
So rare it was only discovered in 1976, with fewer than 100 individuals observed since, despite reaching over 5 metres in length.
🌊 12–250 m
- ⚡ A species discovered only in 1976, one of the major zoological discoveries of the 20th century
- ⚡ A mouth that can open over a metre wide to filter plankton
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.
🌊 100–1300 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
Tiger shark
Galeocerdo cuvier
Tiger shark
Nicknamed "the wastebasket of the sea" for its extraordinarily opportunistic diet, it has been known to swallow objects as improbable as licence plates or tyres.
🌊 0–350 m
- ⚡ The most varied diet known in any shark, including non-food objects
- ⚡ Teeth able to slice through the shell of an adult sea turtle
Atlantic bluefin tuna
Thunnus thynnus
Atlantic bluefin tuna
One of the fastest fish in the ocean, able to keep its muscles warmer than the surrounding water to cross the Atlantic during its migrations.
🌊 0–250 m
- ⚡ Can keep its muscle temperature above that of the surrounding water (regional endothermy)
- ⚡ Top speed among the highest of all bony fish
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.
🌊 0–1280 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