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Figure 23.— Distribution and abundance of Ensis directus in the New York 

 Bight apex. 



Figure 24. — Distribution and abundance of Polygordius triestinus in the New 

 York Bight apex. 



chusetts and New York and recreational clamming account for the 

 east coast harvest. 



Phylum Annelida 



Class Polychaeta 



Order Archiannelida 



Polygordius triestinus Hempelmann, 1906 



DESCRIPTION: Polygordius triestinus is a member of a group 

 called the archiannelids, a heterogeneous assemblage of small 

 worms that have been considered either derivatives of several poly- 

 chaete families or specialized relicts of the ancestral polychaete 

 stock. Polygordius triestinus, adapted for interstitial life, is a very 

 slender worm, lacking obvious external annulation, eyes, and 

 setae. Its only appendages are two cylindrical tentacles projecting 

 from the head and two cirri projecting from the pygidium. Gosner 

 (1971j reported them to be <15 mm in length; Fauvel (1927) 

 reported them reaching lengths up to 30 mm. 



DISTRIBUTION: Very little is known about the distribution of 

 this species, however, Gosner (1971) classified it as a Virginian 

 species, occurring from Cape Cod to Cape Hatteras. 



HABITAT: An unidentified species of Polygordius was the most 

 abundant macrobenthic species in clean medium grain sand off the 

 Delmarva Peninsula (Maurer et al. 1976). Figure 24 and Table 1 

 indicate that P. triestinus was generally associated with sandy (pri- 

 mary medium-grain) sediments with low to medium organic con- 

 tent in the New York Bight apex. 



FEEDING ECOLOGY: The antennae of this genus are actively 

 cast about in front of it as it crawls along, very much as in some of 

 the spionid polychaetes. Similarly, Polygordius spp. are deposit 

 feeders (Hermans 1969). 



REPRODUCTION AND GROWTH: Fauvel (1927) believed P. 

 triestinus to be hermaphroditic. However, hermaphroditism in this 

 species is doubted by Schroederand Hermans (1975) because they 

 believe that the coexistence of eggs and sperm observed in a single 

 individual by Hempelmann (1906) was the result of fertilization, as 

 has been shown in another archiannelid, Protodrilus sp. by Jager- 

 sten (1952). Gosner (1971) also reported sexes to be separate in 

 most archiannelids. Salensky (1907) pointed out that some species 

 of Polygordius released their eggs by a breaking off of the posterior 

 end of the spawning adult. He suggested that such behavior may 

 represent the origin of epitoky and stolonization found in a number 

 of polychaete families. MacBride (1914) and Hermans (1969) 

 stated that Polygordius spp. exhibit the primitive pattern of poly- 

 chaete development by producing well developed planktotrophic 

 trochophore larvae. 



17 



