STUDIES ON THE LIFE HISTORY OF THE MARINE ANNELID NEREIS VEXILLOSA

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Abstract
N. vexillosa Grube deposits its eggs in firm irregular gelatinoid masses varying in size from about 1 to 3 inches in diam. Spawning of small (6-8 cm. long) hetero-nereids occurred at Friday Harbor, Wash., an hour or 2 before midnight during July and Aug. The egg masses are demersal. Heteronereis [female][female] were induced to spawn by introduction of spermatozoa into the water. Young worms hatched from collected egg masses were transported from Friday Harbor, Wash., to La Jolla, Calif., where they throve on fresh animal food and attained a length of 10 cm. (125 segments) at the age of 13 months. None became heteronereized. The process of cephalization is as in other nereids. Since the maximum size of the reared worms is comparable to that of the small spawning heteronereis forms, it appears that the latter were spawning at the age of 1 yr. Much larger nereis and heteronereis individuals are known to occur but the time and steps involved in their development are unknown.

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