Aeglidae

Aeglids resemble squat lobsters in that the abdomen is partly tucked under the thorax. The notable sexual dimorphism in the abdomen is related to the behaviour of carrying fertilised eggs on the pleopods.^[4] The carapace length of the largest species may approach 6 cm (2.4 in), but most are considerably smaller.^[3]

Aeglids are omnivorous, preferring plant matter, but also eating adult insects, molluscs, fish and fly larvae.^[5]

The internal anatomy has been described for Aegla cholchol and generally resembles that of other anomurans, particularly galatheoid squat lobsters. The morphology of the antennal gland bladder differs from that in other anomurans in having a twisted tubular structure which was interpreted as an adaption to the freshwater lifestyle.^[6]

Aegla, the only extant genus in the family, contains around 74 described extant species.^[9] Of the 63 species and subspecies described by 2008, two are found in lakes, four in caves, and the remaining 57 are found mainly in rivers.^[3] 42 species are found in Brazil, all restricted to the country's southern and southeastern regions (Rio Grande do Sul alone is home to 24).^[9] Other countries with species are Argentina, Bolivia, Chile, Paraguay and Uruguay.^[3] More than a third of the species are considered threatened,^[3] and in Brazil alone 26 species are officially recognized as threatened, including 8 critically endangered.^[10]