- Acartia negligens
- Acartia plumosa
- Acartia tonsa
- Acidops cessacii
- Acineta tuberosa
- Aconthaspis capillata
- Aconthaspis furcata
- Aconthaspis hastata
- Acrobotrys spp.
- Acrocalanus andersoni
- Acrocalanus gibber
- Acrocalanus gracilis
- Acrocalanus longicornis
- Acrocalanus monachus
- Acrosphaera murrayana
- Acrosphaera spinosa
- Actae acantha
- Actinomma antarcticum
- Actinomma arcadophorum
- Actinomma leptodermum
- Actinomma sol
- Actinotricha saltans
- Aegina citrea
- Aeginura grimaldii
- Aegisthus aculeatus
- Aegisthus mucronatus
- Aegyriana oliva
- Aepinus septemspinosus
- Aequorea coerulescens
- Aequorea conica
- Aequorea forskalea
- Aequorea macrodactyla
- Aequorea pensilis
- Aetideopsis carinata
- Aetideopsis minor
- Aetideopsis rostrata
- Aetideus acutus
- Aetideus armatus
- Aetideus australis
- Aetideus giesbrechti
- Aetideus pseudarmatus
- Afromysis hansoni
- Agalma elegans
- Agalma okeni
- Aglantha digitale
- Aglantha elata
- Aglaura hemistoma
- Aglauropsis conanti
- Aglauropsis edwarsii
- Aglauropsis kawari