- Pinnixa aidae
- Pinnixa chaetopterana
- Pinnixa cristata
- Pinnixa patagoniensis
- Pinnixa sayana
- Pinnixia brevipollex
- Pinnotheres emiliai
- Pinnotheres garthi
- Pitho lherminieri
- Plagiopyla nasuta
- Plagusia depressa
- Planes cyaneus
- Planes minutus
- Planktonemertes vanhoeffeni
- Planktonetta atlantica
- Platybrachium antarcticum
- Platypodiella spectabilis
- Platyscelus armatus
- Platyscelus crustulatus
- Platyscelus ovoides
- Platyscelus serratulus
- Platyxanthus crenulatus
- Platyxanthus patagonicus
- Plegmosphaera entodictyon
- Plegmosphaera exodictyon
- Plegmosphaera pachyplegma
- Pleopis polyphemoides
- Pleopis schmackeri
- Pleuraspis bipennis
- Pleuraspis constricta
- Pleuraspis costata
- Pleuraspis sarmentosa
- Pleurobrachia pileus
- Pleuromamma abdominalis
- Pleuromamma borealis
- Pleuromamma gracilis
- Pleuromamma piseki
- Pleuromamma quadrungulata
- Pleuromamma robusta
- Pleuromamma xiphias
- Pleuronema crassum
- Plotohelmis alata
- Plotohelmis capitata
- Plotohelmis tenuis
- Pneumoderma atlanticum atlanticum
- Pneumoderma atlanticum boasi
- Pneumoderma atlanticum souleyeti
- Pneumoderma mediterraneum
- Pneumodermopsis brachialis
- Pneumodermopsis macrochira