. The Biological bulletin. Biology; Zoology; Marine biology. AIR-GAPING BY MODIOLUS 63 During these experiments, a few mussels were tested for responses to crudely- applied photic and mechanical stimuli. Photic stimuli were applied with a micro- scope lamp and mechanical stimuli were light taps on the apparatus. The site of photosensitivity appears to be located in a row of darkly-pigmented, white-edged cells on the margin of the siphons. In air or water, mussels respond rapidly to either stimulus by closing. When the stimulus is removed, the valves are returned to their original position. A r
. The Biological bulletin. Biology; Zoology; Marine biology. AIR-GAPING BY MODIOLUS 63 During these experiments, a few mussels were tested for responses to crudely- applied photic and mechanical stimuli. Photic stimuli were applied with a micro- scope lamp and mechanical stimuli were light taps on the apparatus. The site of photosensitivity appears to be located in a row of darkly-pigmented, white-edged cells on the margin of the siphons. In air or water, mussels respond rapidly to either stimulus by closing. When the stimulus is removed, the valves are returned to their original position. A rapid reduction in light intensity elicits this response. Reapplication of this stimulus immediately after a response elicits a smaller, or no, second response. This attenuated response is usually known as habituation. c 0 u L a. 100 if) o 50 O) 10 1 \ o—o Weight •—• Percent. E ro cn 10 30 50 70 Shell height in millimeters Figure 1. Semi-logarithmic plot of the per cent weight loss and actual weight loss as functions of shell height for 39 mussels after 49 hours of desiccation at ° C. and 80% The weight losses are logarithmic and the shell height is arithmetic. The 4 smallest mussels in the plot are dead, the rest alive. Charles (1966) noted that many bivalves have photosensitive mantles and Tauc (1966) reports that gastropods exhibit habituation to both photic and mechanical stimuli. Five days was the median time to death for mussels in a nitrogen atmosphere. In air, the time increased to 9 days, and 13 days was observed for mussels in oxygen. Survival time is proportional to the volume of oxygen present. Kuenzler (1961) noted that these mussels can survive for 28 days out of water when protected from direct sunlight. Unquantitated observations indicate that aerial survival times may be on the order of months in cold, moist Please note that these images are extracted from scanned page images that may have been digitally enhanced for reada
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