The Annual Cycle of Oogenesis, Spawning, and Larval Settlement of the Echiuran Listriolobus pelodes off Southern California

Pilger, John F.
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University of Hawaii Press
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Listriolobus pelodes lives in aggregated populations in fine-grained sediments along the mainland shelf from northern California to Baja California, Mexico. This echiuran forms U-shaped burrows and uses its proboscis to feed on the uppermost layer of sediment deposited around the burrow apertures. The bacterial flora of the sediment may be an important food source. Commensals in the burrow include a polychaete, a pinnixid crab, and a small bivalve. The annual reproductive cycle of a population off Palos Verdes, California, is defined in terms of coelomic oocyte dynamics, spawning, and larval settlement. Small oocytes are released from the gonad through most of the year but fully grown oocytes are present only from mid-fall through spring. It is estimated that the coelomic phase of oogenesis lasts about 5 months. Fully grown oocytes are removed from the coelomic fluid in the germinal vesicle stage and accumulate in the storage organs until spawning. Spawning takes place in winter and spring and individuals are spawned out by summer. An annual influx of small juveniles into the population occurs in late winter and spring. The newly settled juveniles reach sexual maturity when they are 6 months to 1 year old.
Pilger JF. 1980. The annual cycle of oogenesis, spawning, and larval settlement of the echiuran Listriolobus pelodes off southern California. Pac Sci 34(2): 129-142.
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