Biology/Natural History: P. californicus is the largest sea cucumber species along the Pacific Northwest coast. The species feeds on organic detritus and small organisms, which it ingests with bottom sediments. The primary predators of P. californicus are the sea stars Pycnopodia helianthoides and Solaster endeca, but the species is also occasionally eaten by sea otters and man. Unlike many tropical sea cucumbers, P. californicus does not store substances toxic to predators. The hindgut bears a pair of highly branched diverticula, which project into the coelomic cavity of the body and serve as "water lungs". Oxygenated water is pumped into these respiratory trees in several successive inhalations and then expelled in one powerful exhalation. Breeding occurs in the summer. Development is indirect. The sperm have spherical heads and an unusually low DNA content. The fertilized eggs develop into auricularia larvae which metamorphose into doliolaria larva which settle. The pelagic phase lasts from 7 to 13 weeks in the laboratory. Populations of P. californicus in the Puget Sound eviscerate (photo) during October and November and then regenerate new sets of organs. Evisceration may also occur if the animals are kept in warm or stale water. The scale worm Arctonoe pulchra may occur as a commensal on P. californicus.