- Anapronoe reinhardti
- Anasimus fugax
- Anasimus latus
- Anchialina truncata
- Anchialina typica
- Anchylomera blossevillei
- Ancistrocheirus lesueurii
- Andaniexis abyssi
- Andaniexis australis
- Anigsteinia clarissima
- Annatiara affinis
- Anomalothir furcillatus
- Antarctissa spp.
- Anthocyrtidium ophirense
- Anthocyrtidium zanguebaricum
- Apiomithrax violaceus
- Apolemia uvaria
- Appendicularia sicula
- Arachnocorys circumtexta
- Arachnomysis leuckarti
- Arachnomysis megalops
- Arachnopsis filipes
- Arachnosphaera myriacantha
- Aratus pisonii
- Archaeoscina steenstrupi
- Architeuthis dux
- Arctapodema ampla
- Arctapodema antarctica
- Arenaeus cribrarius
- Argonauta argo
- Arietellus aculeatus
- Arietellus giesbrechti
- Arietellus minor
- Arietellus pavoninus
- Arietellus plumifer
- Arietellus setosus
- Arietellus simplex
- Armases angustipes
- Armases benedicti
- Armases miersii
- Arthromysis magellanica
- Artostrobus annulatus
- Ascampbelliella acuta
- Ascampbelliella armilla
- Ascampbelliella obscura
- Ascampbelliella urceolata
- Aspidisca lynceus
- Astracantha heteracantha
- Astrolithium bulbiferum
- Astrolithium piriforme