Electric eel

A living battery of 860 volts

This fish makes electricity! Its body holds thousands of tiny 'batteries' that together give 860 volts — 4 times a household socket. It stuns fish with shocks and finds its way through dark muddy water like radar. It isn't really an eel but a relative of knifefish. It lives in the Amazon and surfaces to gulp air.

The electric eel (Electrophorus electricus, plus 2 species split off in 2019) is a knifefish up to 2.5 m long from the Amazon and Orinoco basins — not related to true eels. 80% of its body is three pairs of electric organs: 6,000 electrocyte cells stacked in series like a battery deliver up to 860 V (E. voltai) and 1 A. Three modes: weak pulses for electrolocation and communication; a strong discharge to stun prey (forcing muscle contraction), even leaping out of the water to attack (Humboldt saw this with horses in 1800). It gets 80% of its oxygen from air, surfacing every 10 minutes. Volta's 1799 'voltaic pile' was inspired by this fish. Rarely fatal to humans, but very painful.

Fun facts

• An electric eel produces 860 volts — 4 times a wall socket.
• It leaps out of the water to shock its target.
• The first battery (1799) was inspired by this fish.