Shocking behavior: How electric eels zap their prey

The animal world’s strongest bioelectricity generator, these fish use electrical fields for hunting and defense, not just communication and navigation.

By Diana Marques

Published August 14, 2020

One species of electric eel, Electrophorus voltai, has recently been observed living and hunting in groups of up to a hundred individuals. Their collective hunting strategy and high discharge helps them overwhelm active shoals of small prey.

Most of the day and night eels rest as a group at the bottom of lakes.

At dawn and dusk, when light intensity is low, they migrate to a shallow hunting area.

Herding thousands of small fish into a prey ball, they take turns zapping them.

Stunned fish fly up, fall back into the water, and get swallowed alive.

Seven minutes later they zap again. In about one hour eels can launch five to seven predatory attacks.

When it comes to electricity generation, E. voltai reigns supreme among all three electric eel species. Their charge can be seven times stronger than a wall socket’s.

E. voltai

860 V

E. varii

572 V

E. electricus

480 V

120 V

E. voltai

860 V

E. varii

572 V

E. electricus

480 V

120 V

Electric eel anatomy is very unique. Eighty percent of the body is taken up by three electric organs, confining the vital organs to a small area behind the head.

Sachs’s electric organ

Main

Vital organs

Hunter’s

Max. length: 8 ft

Sachs’s electric organ

Main

Vital organs

Max. length: 8 ft

Hunter’s

Intestine

Pores in the head and body have receptors that detect electrostatic fields.

Stomach

Gonad

(female)

Liver

Heart

Breathing organ

Thousands of excitable cells called electrocytes make up the eel’s electric organs. The voltage one individual can generate is the sum of all the small charges produced by the electrocytes.

Spinal cord

Swim bladder

Pores in the head and body have receptors that detect electrostatic fields.

Kidney

Stomach

Intestine

Liver

Gonad

(female)

Heart

Thousands of excitable cells called electrocytes make up the eel’s electric organs. The voltage one individual can generate is the sum of all the small charges produced by the electrocytes.

Breathing organ

Spinal cord

Swim bladder

Pores in the head and body have receptors that detect electrostatic fields.

Kidney

Stomach

Intestine

Liver

Gonad

(female)

Heart

Thousands of excitable cells called electrocytes make up the eel’s electric organs. The voltage one individual can generate is the sum of all the small charges produced by the electrocytes.

Breathing organ

Spinal cord

Swim bladder

Pores in the head and body have receptors that detect electrostatic fields.

Kidney

Stomach

Intestine

Thousands of excitable cells called electrocytes make up the eel’s electric organs. The voltage one individual can generate is the sum of all the small charges produced by the electrocytes.

Liver

Gonad

(female)

Heart

Breathing organ

Electric eels are found in tropical South America. E. varii evolved in lowland waters that were murky, slow flowing, and mineral-rich. E. electricus and E. voltai adapted to highland rivers where water is clear and mineral-deprived.

E. varii

7.1 million years ago

E. electricus

3.6 mya

E. voltai

GUYANA

SURINAME

FRENCH

GUIANA (FR.)

COLOMBIA

Eel

sample

AMAZON

ECUADOR

BASIN

BRAZIL

PERU

500 mi

500 km

E. varii

7.1 million years ago

E. electricus

3.6 mya

E. voltai

GUYANA

SURINAME

FRENCH GUIANA (FR.)

COLOMBIA

AMAZON

Eel sample

ECUADOR

BASIN

PERU

BRAZIL

500 mi

500 km

Development: Kennedy Elliott, NG staff. Video: Douglas Bastos and Gabriel Verçoza. Sources: David Santana, Smithsonian Institution; Douglas Bastos, INPA; Philip Stoddard, Florida International University