Sunlight never reaches them, so evolution stopped bothering with normal. Counting down to one animal whose eyes are the size of dinner plates.
It perches on rock a mile down in the Gulf of Mexico and folds its ring of tentacles shut around anything that drifts in — the same trick as the plant it is named after.
A woodlouse the size of a cat, reaching about 50 cm. Food is so rare down there that one in a Japanese aquarium refused to eat for five years straight.
It stands on three stiffened fin rays up to a metre long, facing into the current. Nearly blind, it feels for passing prey with its outstretched front fins.
It swims by flapping two ear-shaped fins. One was filmed at 6,957 metres in the Java Trench in 2020 — the deepest any octopus has ever been recorded.
Found in 2005 beside hydrothermal vents south of Easter Island. The hair on its claws is a garden: it grows bacteria there, then eats them.
The glow on her lure comes from bacteria living inside it. She grows to about 18 cm; the male of the species never gets past 3 cm.
Neither squid nor octopus — it sits alone in its own order. It cannot make ink, so when threatened it squirts a cloud of glowing mucus instead.
Its family has been around roughly 125 million years. To feed, it slingshots its whole jaw forward out of its head — the fastest bite of any shark.
Up to 13 metres long, with eyes 27 cm across — the largest in the animal kingdom. Nobody managed to film one alive in the deep until 2012.
Less than a third of the sea floor has been surveyed in detail. Every deep-water expedition still comes back with animals nobody has named.