Freshwater shrimp (Paratya)

Taxonomic group

Atyidae: Paratya

Diagnostic features

Paratya is our most common freshwater shrimp. The first walking legs lack the large chelipeds (pincers) of crayfish, but instead the ends of these legs are covered in tufts of hairs. Unlike crayfish, Paratya can hover in the water by beating paddle-like appendages under their abdomen. When live the body is almost transparent, but when preserved the body is often white or orange.

[Paratya]. Image: Stephen Moore Image — Paratya. Image: Stephen Moore

[Paratya] - preserved specimen with eggs. Image: Stephen Moore Image — Paratya - preserved specimen with eggs. Image: Stephen Moore

Typical habitats

Paratya have a marine stage in their life cycle so they are most common in coastal streams with slow flow, or rivers downstream of major dams.

Feeding

They can feed by collecting fine organic matter, or by shredding plant matter, or they will eat invertebrates like chironomid midges.

Indicator value

Hard bottom: 5
Soft bottom: 3.6

The tolerance values (ranging from 0 to 10) give an indication of which are the sensitive taxa (values of 8 or more) and which are the tolerant taxa (values of 3 or less). For more information see: Indicator species

Paratya are associated with coastal and slow-flowing streams and rivers, and they are known to occur in streams with only moderate water quality. They have been assigned tolerance values of 5 (hard bottom sites) and 3.6 (soft bottom sites).