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Estuarine isopods (Paranthura)

Taxonomic group

Paranthuridae: Paranthura

Diagnostic features

The freshwater paranthurid isopods have elongated bodies, making them look quite unlike the more familiar slater-shaped isopods. Paranthura is easily distinguished from the similar-shaped Cruregens by the presence of eyes (not visible in Cruregens). Paranthura usually has some speckled grey pigmentation, while Cruregens is generally pale.

Typical habitats

Paranthura is usually found in or near estuaries, and may therefore not be a true freshwater species.


Related isopods are known to feed on algae and other components of biofilms.

Indicator value

  • Hard bottom: unassigned; Order Isopoda value 5
  • Soft bottom: unassigned; Order Isopoda value 4.5

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

Paranthura are probably more an indication of estuarine influence than any other aspects of water quality. There are no tolerance values assigned to this genus but the Order Isopoda has been assigned tolerance values of 5 (hard bottom sites) and 4.5 (soft bottom sites).