- Pacific Ocean
- pagurid
- palatine
- palatoptergoid
- papilla
- parasites
- parietal
- parturition
- pectinate
- pectoral
- peduncle
- pelates
- pelecypods
- pelerins
- pelon
- pelvic
- pennant
- pentagon
- penultimate
- peritoneum
- pharyngeal teeth
- photogenic
- photophore
- phylum
- phytoplankton
- pigment
- piscivorous
- plankton
- pleurotremata
- plicae
- polar
- polychaetes
- population
- posidonia
- postadult
- posterior
- postlarvae
- postmetamorphic
- postorbital
- pouch
- pout
- prawn
- preanal
- prebranchial
- precaudal pit
- predator
- predorsal
- premaxillae
- prenarial
- preopercle
- preoral
- preorbital
- prepectoral
- procurrent rays
- prosobranch
- protandry
- protogeny
- protractile
- protraction
- protruded
- proximal
- pseudo-oceanic
- pseudobranch
- pteropods
- pterygiophore
- punctate
- pungent
- pupil
- pyloric caeca