Fauna
Invertebrate · GBIF taxon 2219853

Gammarus pulex

Gammarus pulex

Also known as Freshwater Shrimp, River Scud, Freshwater Scud

Freshwater scuds dart sideways across riverbeds and tuck beneath submerged stones, shredding autumn leaf litter into vital nutrients that fuel stream food webs. Males clasp females with enlarged gnathopods in a prolonged precopulatory pairing, carrying them for days until a seasonal molt permits mating. Their vulnerability to pesticide runoff and dissolved oxygen drops makes them reliable living indicators of water quality.

FreshwaterBenthicBioindicator
Gammarus pulex reference1 / 2
Licensed reference(c) Nicola Simoncini, some rights reserved (CC BY), uploaded by Nicola Simoncini · cc-by
—observations
—countries
—peak records
Not EvaluatedConservation statusIUCN Red List categoriesLCNTVUENCREWEXNot Evaluated — not placed on the risk ladderRed List categories, explained →
Key facts
Diet & prey
  • Conditioned leaf litter
  • Benthic algae
  • Aquatic biofilms
Predators
  • Brown Trout
  • Eurasian Perch
  • Dragonfly Nymphs
ThreatsAgricultural runoff, organic water pollution, habitat siltation, and invasive amphipods
HabitatsWell-oxygenated streams, rivers, springs, and littoral zones of lakes
Life span1–2 years
Classification
  1. OrderAmphipoda
  2. FamilyGammaridae
  3. GenusGammarus
  4. SpeciesGammarus pulex
Range & activity
Range data is not available yet.
Safe observation
Interaction riskLow
  1. Low
  2. Moderate
  3. High
  4. Very high
Why interaction risk is low
Safe to observe at a normal distance.
Responsible observation
  • Pebble turning: Gently lift smooth stones in shallow, running water to find individuals scuttling along the underside.
  • Habitat preservation: Carefully return displaced gravel and leaves to maintain the microhabitats they require for shelter.
Related species
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