2005 



Whittaker, Robert H. 197 0. 



Communities and Ecosystems. MacMillan Co., New York, xi+158 p. 



No mention of Mercenaria (Venus) mercenaria. - J.L.M. 



2006 



Whyte, Martin A. 1975. 



Time, tide and the cockle. In Growth Rhythms and the History of the Earth's 

 Rotation. G. D. Rosenberg and S. K. Runcorn (eds.) . John Wiley & Sons, 

 London: 177-189. 



Cerastoderma edule and C. glaucum, like Mevcenaria mercenaria, calcify at 

 night. References to hard clam are by citation of papers abstracted 

 elsewhere in this bibliography. - J.L.M, 



2007 



Wiederhold, Michael L., and Edward F. MacNichol, Jr. 1970. 



Only decreases in illumination elicit spike responses in the siphonal 

 photoreceptor system of the hard-shell clam, Mercenaria mevcenaria. Biol. 

 Bull. 139(2): 442-443 (abstract). 



M. mercenaria responds to dimming of light by retracting the siphon and 

 closing the shell. Presumably this is a protective reflex used to withdraw 

 the siphon when the shadow of a predator passes over. Spike responses were 

 recorded from axons in the siphonal nerve which could bring about this 

 reflex. Only off-responses to light were observed, never responses to 

 onset of illumination. It is suggested that receptor cells probably lie 

 near the surface of the inner siphon wall, which is yellow-pigmented. 

 - J.L.M. 



2008 



Wiederhold, Michael L. , Edward F. MacNichol, Jr., and Allen L. Bell. 1973. 



Photoreceptor spike responses in the hardshell clam, Mercenaria mercenaria. 

 J. Gen. Physiol. 61(1): 24-55. 



Spikes were recorded from single axons of siphonal nerve of hard clam, which 

 respond to dimming of light. No axons responded to onset or increase of 

 illumination. In a dark-adapted state little or no spike activity was seen. 

 The responsive area of a single axon was a circle of approximately 85 urn 

 diam on the inner siphon wall. The number of spikes elicited by the off- 

 phase of constant-duration flashes grows as approximately the 0.4 power of 

 flash intensity. At constant intensity and constant light-time fraction the 

 off-response increases with increasing duration at least up to 500 sec 

 duration. For long durations the response grows as the logarithm of stimulus 

 duration. Subthreshold light can suppress the off-response from preceding 

 illumination. In light-adapted state the off-response is greater and its 

 latency shorter than in dark-adapted state. The fine structure of groups of 

 cell processes believed to compose the photoreceptor is described and 

 illustrated. It is suggested that phototransduction occurs in the fine 

 distal processes of the axons, which contain well-organized pentalaminar 

 whorls which may be the site of photopigment concentration. The action 

 spectrum obtained from integrated responses of nerve bundles appeared to be 

 that of a single Dartnall pigment with maximal absorption at about 510 nm. 

 - modified authors' abstract - J.L.M. 



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