River flea cancer

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River flea cancer
Gammarus fossarum Podkomorské lesy.jpg

River flea shrimp ( Gammarus fossarum )

Superordinate : Satchel Shrimp (Peracarida)
Order : Flea crabs (Amphipoda)
Subordination : Gammaridea
Family : Gammaridae
Genre : Gammarus
Type : River flea cancer
Scientific name
Gammarus fossarum
Koch , 1835

The river flea shrimp ( Gammarus fossarum ) is a flea shrimp from the Gammaridae family and a typical brook inhabitant .

In 2021 he was named Animal of the Year in Switzerland .


This species becomes up to 14 mm (females) or 21 mm (males) long. It is compact in shape with a dark, mostly brownish shell.


The river flea shrimp, together with the common flea shrimp ( Gammarus pulex ) and the river flea shrimp ( Gammarus roeselii ), are among the most frequent inhabitants of the small and medium-sized rivers of Central Europe. Often the last two amphibians mentioned are also known colloquially as river amphibians because of their similarity to Gammarus fossarum . Gammarus roeselii can be distinguished from the other species by the keeled segments on its back. Gammarus fossarum also occurs at altitudes above +450 m above sea level, whereas Gammarus pulex is generally no longer to be found there.

Under favorable conditions there is a mass reproduction of the river flea shrimp. Here there are often collections of several thousand individuals per square meter.


The river flea shrimp feeds mainly on fallen leaves, but also on all kinds of organic food particles that can be filtered out of the water. Cannibalism has also been observed.

Saprobic index

The saprobic index for this species is 1.3.


  • Goedmakers, A., Gammarus fossarum: Rediscription based on neotype material and notes on its local variation (Crustacea, Amphipoda). , Bijdragen tot de Dierkunde 42, 1972, p. 124-138.

Web links

Individual evidence

  1. The river flea cancer is the animal of the year 2021. Pro Natura, January 3, 2021, accessed on January 3, 2021 .
  2. kaeferatlas.de, accessed June 1, 2015
  3. a b Meyer, Detlef .: Macroscopic biological field methods for assessing the water quality of rivers: with lists of species for beginning and experienced investigators and detailed descriptions and images of the indicator organisms . 4th, unchanged. BUND, Hannover 1990, ISBN 3-9800871-4-X .