Understanding of Rhithropanopeus harrisii was summarised by Brockerhoff and McLay (2011) and Global Invasive Species Database (2020). Recent research on Harris mud crab includes monitoring using citizen science in the Finnish Baltic Sea, an area without native crabs (Lehtiniemi et al., 2020). Because it is an introduced species, research  on the species’ biology  continues attract interest. For example, in the Baltic Sea, its susceptibility to parasitism (Tepolt et al., 2020) and pollutants (Wilman et al., 2019) have been investigated. A valuable compilation of ecological and life-history information is available in Aarnio et al. (2015).

Adult crabs would be expected in estuaries and freshwater lakes near the sea preferring a temperature range of 20–25°C. It is typically found sheltering under rocks or vegetation in shallow water.

The shell (carapace) of the Harris mud crab carapace is about 1.3 times as wide as long, with the sides converging posteriorly. The front, between the eyes, occupies a third of the carapace width. The carapace is greenish-brown to olive green with white underneath and reaches 20 mm wide. The claws have white tips. The distinguishing features are the four lobes on each side separated by triangular clefts, the last two being sharper.

The species is not so far known from Australia.