Acadian hermit crab 
Achaeus spinosus 
Adinda lamellata 
Aggtelek Blind Sideswimmer 
Alcyonohippolyte dossena 
Aliaporcellana spongicola 
Allogalathea babai 
Amazon freshwater crab 
Amazon River Prawn 
Ambiguous Crayfish 
American lobster 
Ancylomenes longicarpus 
Ancylomenes pedersoni 
Ancylomenes sarasvati 
Anemone hermit crab 
Anker's whip coral shrimp 
Ant Woodlouse 
Arachnothelphusa merarapensis 
Arcitalitrus dorrieni 
Arrow Crab 
Arrowhead crab 
Astacoides crosnieri 
Astacus astacus 
Atlantic ghost crab