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WHIRLIGIG BEETLES

GYRINIDAE 

GYRINIDAE—Whirligig Beetles

family

Gyrinidae

known species

1,000

distribution

Worldwide except Antarctica

habitat

Still, fresh water such as ponds and lakes,

as well as slow-moving rivers and streams.

Some species live in brackish water such

as rock pools

size

3–15 mm

diet

Larvae are active hunters below the water,

while adults generally feed on drowned and

drowning insects that have become trapped

in the surface tension

T

he Gyrinidae is a small family of fewer than

1,000 species of small-sized beetles, found

throughout the world, including Europe and North

America. Despite their small size, they are well

known and conspicuous, as adults can be seen in

large numbers on the surface of still or slow-flowing

water, moving in a very rapid, erratic, seemingly

random motion, which has earned them the name

“whirligigs,” after old-fashioned spinning-top toys.

They are predators, hunting on the surface tension

of the water, and are constantly “reading” the

ripples, which alert them to the presence of

drowning insect prey.

Whirligigs are remarkable for having the eyes

of the adults divided, one half observing the air

above, the other watching for danger in the water

below. They give the appearance of having four eyes,

below | Gyrinus A European whirligig beetle on

the surface tension, showing the upper part of the

divided eyes and flaplike back pairs of legs.