REPRODUCTION IN SEA ANEMONE 481 



would take a minimum of 10 days to develop free spermatozoa from 

 primary spermatocytes in the opisthobranch Phyllaplysia taylori. 

 Only 9 days were required in the sea urchin Strongylocentrotus 

 piirpuratus (Holland and Giese, 1965). 



Despite the delayed and compressed cycle exhibited by outfall 

 males, these anemones spawn at about the same time as do their 

 control counterparts. Anemones in the outfall began spawning 

 sometime after July 21 and had finished by Sept. 17, 1974, and 

 control animals spawned during the same period. In 1975, no 

 spawning was observed in the outfall, but, since ripe gonads were 

 found on July 11 and no gonads could be seen by Aug. 8, we can 

 infer that spawning occurred between these two dates. In the 

 control, anemones were spawning on Aug. 8. Not until 1976 was 

 there an appreciable difference in the timing of spawning of the two 

 populations. All outfall anemones collected on July 13, 1976, had 

 spawned; others in the same clone were still ripe or spawning on 

 Aug. 11; but all had spawned by the end of September. In the 

 control, complete spawning took place between Aug. 11 and 

 Sept. 27. 



In the transplant experiment, outfall, control, and outfall caged 

 but not transplanted anemones all showed very similar oocyte 

 size-frequency histograms (Fig. 6). Control anemones that were 

 transplanted to the outfall underwent a rapid maturation, however. 

 Of six anemones sectioned, two were ripe, and three more had 

 recently spawned. This occurred during a period of increasing 

 temperature in the outfall (the temperature at the time of the March 

 collection was around 22° C), and it appears that increasing tempera- 

 ture accelerated vitellogenesis and induced spawning in anemones 

 from the cold-water control area. Anemones acclimated to the 

 outfall do not normally spawn until summer, when the outfall 

 reaches its average maximum temperature of 25°C, but by March 

 1976 the control anemones that were transplanted into the outfall 

 were already 7°C past the 15°C maximum that the control area 

 reaches in summer. 



CONCLUSIOIMS 



The sea anemone Anthopleura elegantissima reproduces on an 

 annual cycle at Morro Bay, with gametogenic cells being visible first 

 in late fall and winter and spawning occurring in late summer in 

 natural populations. 



Males of A. elegantissima from a thermal-outfall canal exhibit a 

 delayed onset of gametogenesis but spawn as much as 1 month 



