Scuds (Hyalella)
Hyalella azteca · Aquatic life
Whole animal · Photo: Dr. Andrew G. Cannizzaro / CC BY
Also called Hyalella azteca, Side swimmers, Amphipods, Freshwater shrimp
How to identify Scuds (Hyalella)
- Small shrimplike animals up to about 1/3 inch
- Body flattened side to side and curved
- Swim on their side in quick darts
- Pale, greenish, tan or purplish
- Often in huge numbers in plant beds and algae mats
Similar species
Gammarus scuds are larger, up to about 3/4 inch, with more hair and spines on the tail segments. Aquatic sow bugs are flattened top to bottom and crawl rather than swim.
Profile
| Season | Present all year; populations peak in summer. |
|---|---|
| Starts | Breed most when water is above about 50 F |
| Depth | Shallow plant beds and bottom |
| How it spreads or reproduces | Carried on plants, birds and equipment; several broods a year |
| Habitat | Plant beds, algae mats and leaf litter in ponds, lakes, canals and springs; one of the most widespread freshwater animals in North America. |
Why it matters in a lake
Top tier food for trout, bass and sunfish and a sign of good plant cover. They eat algae, detritus and dead plant material.
Where it is found
- Idaho: Common
- Oregon: Common
- Wyoming: Common
Classification
| Kingdom | Animalia |
|---|---|
| Phylum | Arthropoda |
| Class | Malacostraca |
| Order | Amphipoda |
| Family | Hyalellidae |
| Scientific name | Hyalella azteca |
Signal crayfish
Scuds (Gammarus)
Aquatic sow bugs
Virile crayfish
Red swamp crayfish
Rusty crayfish
Fairy shrimp
Tadpole shrimp
Clam shrimp
Pilose crayfishNeed a hand?
Found it in your lake?
Send us a photo and we will identify it and tell you what it means for your lake.
Idaho / Wyoming (208) 501-4531Oregon (541) 280-0596