POLYCHAETE WORMS, PART 1 217 



G. dibranchiata is 1 of the 2 (along with Nereis virens) common 

 commercially valuable marine bait worms in the Maritime Provinces 

 and in Maine, where it is known as the "bloodworm" or "beak- 

 thrower," because of its habit of extending and retracting the proboscis 

 when handled. The minimum marketable length is about 6 inches. 

 According to Dow and Wallace (1955), bloodworms can apparently 

 tolerate conditions which are unfavorable for both sandworms and 

 quahogs. They are found further upstream than clams in the tidal 

 rivers, Ai'eas affected by considerable amounts of fresh water runoff 

 may be barren of shellfish and sandworms but will be occupied by 

 bloodworms. They were found in the stomach of haddock (Georges 

 Bank, 1953, R. Wigiey). 



Klawe and Diclde (1957) made observations on a population of 

 G. dibranchiata from Goose Bay at Wedgeport, Nova Scotia. They 

 found that in the sexually mature worms, or "spawners," the muscles 

 of the body wall and of the proboscis undergo histolysis, such that 

 they become thin walled and fragile and the digestive tract breaks 

 down. Eggs and sperm begin development in late summer and are 

 sexually mature by early April (fully developed eggs between 180/i and 

 190/x in diameter). The breeding season is restricted to a few weeks 

 in the spring, the peak of the spawning taking place in the middle of 

 May. Spawning was not observed, but remains of spent worms 

 were found on the flats, appearing as "ghost worms," consisting of 

 the outer skin and atrophied digestive tract with everted proboscis, 

 indicating that life terminates after spawning. There was no evidence 

 for swarming at spawning time. 



Their early development was also followed. They develop into 

 planktonic larvae for a time before being transformed into bottom 

 dwellers, but it does not seem likely that they are pelagic during much 

 of their development. From an analysis of the distribution of size 

 classes in the population, Klawe and Dickie surmised that most of the 

 intertidal population lives for 3 years and that they spawn before 

 reaching the fourth year; a small fraction spawn when 4 or 5 years old. 

 Growth is most rapid in the second and thh"d years, decreasing sharply 

 thereafter. According to Moore (ms.) in the Woods Hole region, 

 they breed during the summer but ripe individuals are seldom met 

 with; epitokous individuals are very rare (Klawe and Dickie suggest 

 that they were tardy spawners). 



Adults have been observed swimming at tho surface: Eel Pond, 

 Woods Hole, evening, August 17, 1943, J. B. Buck; Woods Hole, 

 surface, January 28, 1876, Verrill; Delaware Bay, January 29, 1957, 

 T. Hopkins. 



Material examined. — Numerous specimens from Gulf of St. 

 Lawrence (Bay of Chaleurs, low water to 12 fathoms), Nova Scotia 



