Our animals

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Water flea

Water flea

European perch

European perch

Alpine bullhead

Alpine bullhead

Three-spined stickleback

Three-spined stickleback

Swan mussel

Swan mussel

Goldfish

Goldfish

Oriental carp

Oriental carp

Belica

Belica

European crayfish

European crayfish

Bitterling

Bitterling

Gudgeon

Gudgeon

Water flea

Water flea

Facts

LatinDaphnia sp.
Size0.5 cm
FoodPlant plankton
HabitatLakes and ponds
IUCN

Not evaluated

LocationGlobal, except Australia
Map

Tiny crustaceans

The water flea is a tiny crustacean with a transparent shell that makes it difficult for predators to see it. It survives on tiny algae, which it sucks into its mouth by creating a current in the water with its legs.

Helmet and spine

In lakes with many small fry, water fleas develops a sharp helmet on its head and a long spine on the hind part of its body. This spine makes it difficult for small fish to eat it. The water flea discards these defences again if the fish disappear.

Virgin birth

Among water fleas, the females reign most of the year. They reproduce without the presence of male water fleas and only female young are produced. This virgin birth is called pathogenesis. Males are only produced in late summer so they can mate with the females.

Small animal – big impact

When there are large numbers of water fleas present, they can consume 30% of the algae in a lake in a single day. Algae can be a problem in polluted lakes, where large concentrations make the water cloudy and use up all the oxygen in the lake. The voracious appetite of the water flea keeps algae in check, benefiting all animal life in the lake.


Sturgeon

Danish stream

Danish lake

Herrings in the Sound

Boulder reef in the Sound

Stone reefs and jellyfish

Sandy bottom

Eelgrass in the Sound

Faroese bird cliff

Seaotter

Pacific octopus

Japanese spider crab

American lobster