The Alabama cave shrimp is colorless and largely transparent with a total length of up to 20 mm (0.8 in.) (Cooper 1975; Smalley 1961). The only other species of Palaemonias is the endangered Kentucky cave shrimp, P. ganteri, known only from Mammoth Cave, Kentucky. Palaemonias alabamae is very similar to P. ganteri, but is smaller in size, has a shorter rostrum. generally lacks ventral rostral spines and has fewer dorsal rostral spines (Smalley 1961).