Ara
Arabella Grube, 1850
- Arabella aracaensis Steiner & Amaral, 2009
- Arabella atlantica Crossland, 1924
- Arabella caeca Fauvel, 1940
- Arabella cincta Hartmann-Schröder, 1962
- Arabella coeca Fauvel, 1940
- Arabella diversimaxillata Szaniawski & Gazdzicki, 1978 †
- Arabella endonata Emerson, 1974
- Arabella geniculata (Claparède, 1868)
- Arabella iricolor (Montagu, 1804)
- Arabella iridescens Treadwell, 1906
- Arabella logani Crossland, 1924
- Arabella longicirrata Hartmann-Schröder, 1979
- Arabella longipedata Monro, 1931
- Arabella maculifera (Grube, 1878)
- Arabella mimetica Chamberlin, 1919
- Arabella monroi Colbath, 1989
- Arabella mutans (Chamberlin, 1919)
- Arabella nesidensis (Delle Chiaje, 1828)
- Arabella panamensis Colbath, 1989
- Arabella pectinata Fauchald, 1970
- Arabella protomutans Orensanz, 1990
- Arabella renierii (Grube, 1877)
- Arabella rolandi (Delle Chiaje, 1828)
- Arabella semimaculata (Moore, 1911)
- Arabella zonata (Moore, 1903)
Annelida → Polychaeta → Errantia → Eunicida → Oenonidae , Arabellites , Arabelloneris , Aracia
Arc
, Archinome , Arcteobia , Arcteonais , Arctodrilus , Arctonoe , Arctonoella
Are
, Arenicola , Arenicolidae , Arenicolides , Arenotrocha
Arh
, Arhynchobdellida
Ari
, Arichlidon , Aricia , Aricidea , Aristonerilla
Arm
, Armandia
Arr
, Arranooba
Art
, Artacama , Artacamella , Articulatia
Ary
, Aryandes