Phylum Echinodermata 



Class Echinoidea 



Echinarachnius parma (Lamarck, 1816) 



DESCRIPTION: This flat, circular echinoderm is the common 

 sand dollar. It is usually purple-brown in color when alive and unin- 

 jured, but changes to dark green when exposed to air. injured, or 

 recently dead. Size up to 83 mm in diameter (Lohavanijaya 1964). 



DISTRIBUTION: This species is discontinuously circumboreal, 

 being found both in the North Pacific and North Atlantic, but not in 

 Arctic regions. In the western North Atlantic, the known range 

 extends from Cape Hatteras to Labrador and Greenland (Mortensen 

 1948: Durham 1955): Lohavanijaya (1964) reported specimens 

 observed from the Bahamas and Cuba, but Virginia is the limit of 

 the U.S. coastal population. 



HABITAT: Coe (1972) reported that in the northern part of its 

 range. Echinarachnius parma is found near the low water mark, 

 but further south it occurs only in deeper water, to 2,500 m. 

 Lohavanijaya (1964) found them abundant in the surf zone in 

 Maine. In the New York Bight apex, they were located in depths 

 ranging from about 10 to 30 m (Fig. 68), however, they are known 

 to occur in New York-New Jersey outer continental shelf samples in 

 depths exceeding 75 m (Pearce. Caracciolo. Halsey. and Rogers 

 1977a). Stanley and James (1971) reported that the distribution of 

 this species off Nova Scotia can be closely related to mean grain 

 size of sediments. They were most abundant in fine (2-30) to 

 medium ( 1 -2<j>) clean sands, not being found in very fine sand or in 

 well-sorted sand. In the New York Bight apex, this species was also 

 collected almost exclusively in fine or medium sand with an 

 organic content of <3% (Fig. 68; Table 1). Echinarachnius parma 

 is sensitive to anoxic conditions, and while they may be found in 

 areas of organically enriched sediment sublayers, Parker (1927) 

 reported that they will not burrow there. During the anoxic problem 

 in the New York Bight in 1976, the E. parma population in a large 

 area, over 1,000 km 2 , was killed (Steimle and Radosh 1979). 

 Redford (1978) reported that E. parma may also be sensitive to 

 sewer outfalls because of a significant decrease in occurrence and 

 abundance in an area off southern Long Island, 5 yr after the instal- 

 lation of a sewer outfall. 



FEEDING ECOLOGY: E. parma has been reported to be both a 

 deposit and suspension feeder. Stanley and James (1971), Coe 

 (1972). and Timko (1976) regarded this species to be a micropha- 

 gous deposit feeder, subsisting on microscopic organisms, particu- 

 larly diatoms and other algal material. Phelan (1977) reported little 

 or no sand in the intestinal tract, indicating E. parma is a selective 

 feeder. In the Pacific. Sokolova and Kuznetsov (1960) and 

 Zenkevitch (1963) considered the species to be a suspension feeder, 

 based on their observations of high concentrations in some areas, 

 such that individuals touch or overlap. 



Feeding is accomplished by the use of some of the weak tube 

 feet, cilia, and mucus strands (Parker and Van Alstyne 1932; 

 Hyman 1955; Sokolova and Kuznetsov 1960; Phelan 1977), which 

 collect and move food particles along furrows to the ventral mouth. 

 Feeding may occur while the species is on the surface or burrowing 

 in the sediment. 



Ruddell (1977) found that approximately 8% of the sand dollars 

 he examined in the New York Bight had commensal ciliates 



4030 



4 \ 



,\'in 



vV 7 



/ 

 / 



/ 40 20- 



5 i 



□ 100 -m/m* 



4010 



7340' 



i 



Figure 68. — Distribution and abundance of Echinarachnius parma in the New 

 York Bight apex. 



attached to their tests. Similar ciliates were noted on asteroid star- 

 fish. 



Coe (1972) reported that "in many localities, the species [E. 

 parma] is so abundant as to form an important part of the food sup- 

 ply of certain fishes, particularly the flounder, codfish and tautog." 

 In the northwest Atlantic, Maurer and Bowman ( 1975) ,s found E. 

 parma to comprise 94% by weight of the diet of Conger eel. Con- 

 ger oceanicus, 54-71% of the diet of ocean pout. Macrozoarces 

 americanus, and 40-67% of the diet of American plaice, Hip- 

 poglossoides platessoides. 



REPRODUCTION AND GROWTH: Cocanour and Allen 

 (1967) reported that this species spawns during the fall (September- 

 December) in Maine, and Ruddell (1977) reported similar findings 

 in the southern New York Bight. Fewkes (1886) reported the 

 appearance of larvae in September in Rhode Island. Maurer et al. 

 (1976) reported finding juveniles (<5 mm) in early November off 

 Delaware. Graef (1977), " after examining the size distribution of 

 E. parma collected in New York Bight apex samples, suggested 

 that new recruits ( > 10 mm) are available all year but peak in 

 March. Ruddell (1977) found ripe females present from spring 



ls Maurer, R., Jr., and R. Bowman. 1975. Food habits of marine fishes of the 

 northwest Atlantic. Northeast Fisheries Center Data Report. Woods Hole. Mass., 

 Lab. Ref. 75-3. 90 p. 



,9 Graef, J. 1977. A preliminary investigation of the growth rate and natural his- 

 tory of Echinarachnius parma (Lamarck) in the New York Bight apex area. Unpubl. 

 manuscr. . 25 p. Northeast Fisheries Center Sandy Hook Laboratory. National 

 Marine Fisheries Service, NOAA, Highlands. NJ 07732. 



47 



