Gammarus

The genus Gammarus belongs to the crustacean order Amphipoda, specifically within the family Gammaridae, which is the largest family of amphipods. Amphipods, commonly known as scuds, are found in various aquatic environments worldwide, including freshwater, saltwater, and even moist terrestrial habitats.12

Gammarus species are typically small, growing to about 5 to 30 mm (0.2 to 1.2 inches) in length. Their bodies are flattened from side to side, with distinct thoracic and abdominal limbs adapted for walking, swimming, and gliding. These amphipods are ecologically important, often found in abundance among aquatic plants. Their diet varies, with some species feeding on fragmented organic matter, while others are herbivores, carnivores, or external parasites. Eggs and young develop in a ventral brood pouch on the female.1