Crayfish are freshwater crustaceans belonging to the infraorder Astacidea, which also contains lobsters. Taxonomically, they are members of the superfamilies Astacoidea and Parastacoidea. They breathe through feather-like gills.

Naturefile is a celebratory journey to the lesser-known realms of nature in Ireland with Anja Murray.  With surprising stories uncovered each week, about everything from lichens to trees, Swallows to Sea Eagles, starfish and turtles, there are elements of science, history and folklore.