Order Cirratulida 



Tharyx acutus Webster and Benedict, 1887 



DESCRIPTION: Sluggish worms; threadlike bodies. Maximum 

 size 15 mm by 2 mm; has a shallow, mucous-lined burrow (Webster 

 and Benedict 1887). 



DISTRIBUTION: Maine to Virginia. 



HABITAT: Tliaryx acutus was abundant in samples collected on 

 the New York-New Jersey outer continental shelf by Pearce. Carac- 

 ciolo. Halsey. and Rogers (1977a). It was also the most abundant 

 polychaete collected in the New York Bight apex samples, occur- 

 ring throughout the apex in all sediment types. Although it was 

 most common in low organic areas, it was present in concentrations 

 as high as 3.300/m : in high organic sediments (Fig. 50: Table 1). 



FEEDING ECOLOGY: The cirratulids, in general, are surface 

 deposit feeders, gathering food particles from the sea bottom by 

 means of numerous grooved tentacular filaments (Dales 1963; Day 

 1967). However, in some of our Baltimore Canyon Trough samples 

 (Radosh et al. footnote 8). specimens of T. acutus were observed to 

 have consumed the polychaetes Lumbrineris tenuis and Drilonereis 

 magna (Frame footnote 10). 



a closely related species, at Plymouth, England. He found that 7". 

 marioni is capable of spawning over several years, with females 

 breeding for the first time in the second year of life. The main 

 spawning season extends from late October to early November 

 when water temperatures are between 10° and 12°C. As described 

 by Dales (1951), Tliaryx spp. larvae are bottom-living, nonpelagic, 

 and lecithotrophic. Population densities are at their highest level 

 just after spawning has taken place; in Plymouth, the highest densi- 

 ties recorded were approximately 100,000/m : . At that time, juve- 

 niles of the previous year's brood composed about two-thirds of the 

 population and were easily distinguished from the larger adult 

 worms. During spring and summer, population levels gradually 

 declined so that during the breeding season a mean density of only 

 33,000/m : was recorded, of which about 40% were breeding 

 adults. 



In the New York Bight apex, we observed T. acutus to be 1.6 

 times more abundant during winter months, which would indicate 

 that this species may also breed here during fall or winter months. 



Tharyx annulosus Hartman, 1955 



DESCRIPTION: Slow-moving, threadlike worm, slightly 

 smaller than T. acutus. 



REPRODUCTION AND GROWTH: No information is avail- 

 able for T. acutus, however, Gibbs (1971) studied Tliaryx marioni. 



DISTRIBUTION: New England to tropical South America; 

 South Africa (Day 1973). 



r~i i- »»/">•' 



] 100-9??/m ? 

 I 1000-8.179/m 2 



40 20" 



4010- 



7350 



7340' 



I 



40 20- 



7340' 

 I 



Figure 50.— Distribution and abundance of Tharyx acutus in the New York 

 Bight apex. 



Figure : 



-Distribution and abundance of Tharyx annulosus in the New York 

 Bight apex. 



35 



