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
