POLYCHAETE WORMS, PART 1 177 



marine algae is not available, on debris and terrestrial vegetation 

 brought down to the sea; at certain seasons, it may be carnivorous, 

 feeding on other annelids. On breaking the clods of mud, one may 

 find that the walls of the galleries are filled with fragments of Kntero- 

 morpha or Zostera; the animal drags fragments of the algae into the 

 galleries for feeding later. 



Harley (1950) found that it is able to use a filter-feeding mechanism, 

 at least when occupying glass tubes in the laboratory. A filter-feeding 

 funnel, attached in front to the wall of the tube, was made from long 

 threads secreted by the parapodial glands and molded into the shape 

 of a funnel by the parapodial setae. With the undulation of the seg- 

 ments of the body, water with the suspended particles was drawn past 

 the animal anteroposteriorly; particles were sieved out of the water 

 current. At intervals, the worm moved forward and swallowed the 

 feeding funnel with its entrapped particles. 



Dales (1950, 1951), in a study of a population in the Thames estuary 

 in England, and others have found that the sexual adults are atokous 

 (the reports that they may be epitokous are probably due to confusion 

 of species; the closely related A'', japonica Izuka in Japan swarms at 

 the surface, without, however, going through the marked structural 

 changes of the typical heteronereid ; it is only slightly modified, 

 Smith, 1958) and dioecious (some consider that hermaphroditism 

 might occur exceptionally; the closely related A^. limnicola Johnson, 

 which includes A^. lighti Hartman, from California estuaries and fresh 

 water lakes, is a protandrous, self-fertilizing viviparous hermaphrodite, 

 Smith, 1950, 1958). The males are fewer in number than the females 

 (only 10 percent males found by Dales; 40 percent males found by 

 Boguchi, 1954). Under natural conditions both Dehorne (1925) and 

 Dales (1950) have described a kind of pseudocopulation or sexual con- 

 gress in which several females were found around a single male, associ- 

 ated perhaps with the scarcity of males. Herpin (1926) found 1 male 

 to 7 females. In this case, the usual procedure is reversed and the 

 numerous females pursue the scarce males. They may leave their 

 burrows at night and swim in search of males. 



Spawning takes place in the burrow. Dales observed that spawning 

 took place toward the end of Februar}^ when there was a marked rise 

 in temperature between 5° and 8.8° C. Spawning occurs mostly 

 in late winter or early spring but may occur exceptionally throughout 

 the year ir) parts of its range. The eggs are evidently shed by rupture 

 of the body wall. The sperm are discharged through the nephridia 

 or by rupture of the body wall. Females die after spawning. Owing to 

 the comparative scarcity of males and the fact that the females will not 

 spawn except in the presence of a nuile, large numbers of mature fe- 

 males remain unspawned. They eventually die before the following 



