[2] Members of the infraorder Astacidea are found throughout the world – both in the oceans and in fresh water – except for mainland Africa and parts of Asia.

[4] Astacidea is the sister clade to the infraorder Polychelida, a small group of crustaceans restricted to deep waters.

The cladogram below shows Astacidea's placement within the larger order Decapoda, from analysis by Wolfe et al., 2019.

[6] The members of the infraorder Glypheidea (containing numerous fossils and the two extant species Neoglyphea inopinata and Laurentaeglyphea neocaledonica) were formerly included here.

[1] The cladogram below shows Astacidea's internal relationships and the early split between lobsters and crayfish:[5][7][8] Enoplometopidae Nephropidae Parastacidae Cambaroididae Astacidae Cambaridae