FEEDING RATES OF STARFISH, ASTERIAS FORBESI (DESOR), AT CON- 

 TROLLED WATER TEMPERATURES AND DURING DIFFERENT SEASONS 

 OF THE YEAR 



BY CLYDE L. MACKENZIE, JR., FISHERY BIOLOGIST 

 BUREAU OF COMMERCIAL FISHERIES BIOLOGICAL LABORATORY 

 MILFORD, CONNECTICUT 05450 



ABSTRACT 



Starfish were held for 28 days in pans with running 

 sea water maintained at a series of constant tempera- 

 tures, with oysters as food. The average number of 

 oysters eaten per starfish during this period was 2.3 at 

 5° C, 3.0 at 10° C, 4.1 at 15° C, 5.0 at 20° C, 2.8 at 

 22.5° C, and 1.0 at 25° C. Starfish lost weight at 25° C. 

 To observe seasonal feeding rates, starfish and oysters 

 were held in trays suspended in Milford Harbor, Conn. 

 Starfish fed little from mid-January to the end of 

 March, but the rate of feeding then increased rapidly 



to a maximum in late June and early July. After mid- 

 July, starfish fed at about one-third the rate of late 

 June. This second period of low feeding, which appeared 

 to be associated with both high temperatures and 

 spawning, lasted from July through September. From 

 late October through early December the rate of feeding 

 increased again to about two-thirds of the level in late 

 June and early July, before decreasing again to the 

 seasonal low in mid-January. 



Information in the literature on feeding rates of 

 starfisli, Asferias forhesl (Desor), is limited, and 

 no one has reported studies of feeding rates at dif- 

 ferent si^ecific temperatures maintained within 

 ilosely controlled limits. In addition, no one has re- 

 ported quantitative studies that describe possible 

 changes in feeding rates during different seasons of 

 tlie year. Although Galtsoff and Loosanoff (1939) 

 stated that starfish in Ivong Island Sound feed 

 more actively during the summer than during tlie 

 winter, they did not determine specific rates. 

 Xeedler (1941) reported that Asterias vulgaris 

 ( Verrill) in waters of Eastern Canada feed mostly 

 in the spring and fall and relatively little in tlie 

 winter. (In both Long Island Sound and Eastern 

 Canada, water temperatures fall to slightly below 

 0° C. in tiie winter.) According to Hancock (195.-), 

 1958), Axterias rubens L.. which inhabit English 

 waters, feed at a high rate throughout the winter. 

 -Vear P^ssex, England, where the studies were made, 

 water temperatures average 4° to 8° C. during the 

 winter. He reported that tlie only important sea- 

 sonal lull occurs just after the spawning season 

 in May and that feeding increases again sometime 

 between September and November. Because he 



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made no controlled laboratory stiulies of feeding 

 rates at a series of constant temperatures, he could 

 not determine whether the decline in feeding after 

 May was in response to high water temperatures, 

 which rose above 15'^ C, or to spawning. Thoi-son 

 (1955) found that tlie brittle star, Amphiur<t sp., 

 does not feed for 1 month before spawning in late 

 summer; after spawning it lies quiescent on the 

 bottom, not feeding for about another month. 



I have attempted to determine feeding rates of 

 starfish at a series of constant tem[)ei'atures and 

 during different seasons of the year. In tlie study 

 of seasonal feeding, I wanted e,specia]ly to obtain 

 a record of ijossible feeding during winter and to 

 determine whether feeding slows down in inidsuni- 

 luer after starfisli l)egin to spawn. Spawning of 

 starfisli in Long Island Sound begins in th(> middle 

 of June and continues intermittently through the 

 summer ((ialtsoff and I^oosanotf. WY.V.): I.,oosanuff. 

 10()1). During the eN|)erinients I also recorded the, 

 gains and losses in weight of starfish, f believed 

 that such a study would [)ro\ ide important data 

 Mil the biology of >tarHsh and useful in formatimi 

 foi' cDiiuiiei'cial li'rii" ers of shellfisli. 



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