Purnet (1998) has extensively studied the reproduction of Arctonoe spp. and has determined that all three species of Arctonoe  have similar reproductive strategies, periods and ontogenies. The developmental patterns are also very similar to other polynoid species.

Arctonoe spp. broadcast spawn from March until August. The worms become sexually mature at about 4 months of age, in the late spring and early summer when they reach about 2 cm in length. Oocytes cluster on the segmental blood vessels of immature females. A few days before spawning, the oocytes are ovulated into the coelom where they free float before being released through the ventrally directed segmental nephridiophores during the night and early morning. Fecundity is high with over one hundred thousand  80-µm diameter eggs released at a time by each individual female. The spawned eggs are opaque pale yellow and spherical. Males readily spawn at any time of the day, even when they are isolated.

The first polar body is formed 30-40 minutes after fertilization occurs. The first cleavage is present after two hours. The blastulae forms eight hours after fertilization. Ten hours after insemination, trochoblasts which are arranged around the equator of the cell, develop multiple cilia which continue to grow and elongate, facilitating swimming. At 20 hours, the larvae undergo gastrulation and consistently swim to the water surface and congregate. After 36 hours, the large mouth and anus are in their final positions.  The kidney shaped eyes are present after 45 hours, as are several rows of cilia. The "oral brush" is a band of cilia near the mouth which forms after 50 hours. It is characteristic of all polynoid larvae.

5 weeks after insemination the larvae has reached its full size and will remain in the basic larval form until it is about 10 weeks old. After 6 weeks body segmentation begins to take place, as does ventral-dorsal flattening and setae formation. During metamorphosis, the following changes occur;  additional eyes are formed, dorso-ventral flattening continues, the segments become better defined and cirri and elytra develop. The head is fully formed during  late stages of metamorphosis.  The life span of Arctonoe spp. is about 8 months in captivity and several years in the field. The long planktonic larval period of Arctonoe spp. probably leads to high dispersal, suggesting that geographic differentiation in host preferences is unlikely except over large spatial scales.

Note: All of the information and pictures used in this page were obtained from several studies performed by Bruno Pernet, University of Washington. For further information and the citation, see the reference page. The PhD. dissertation, from which this information came, includes an extensive analysis of the life history and reproductive stages of Arctonoe spp. well as genetic analyses that did not fit into the scope of this web page.