. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. HEAT EFFECTS ON A MARINE SNAIL 343 90 80 70 ^60 £50 - X 20 10 '}25°C. o I I I I 05 10 15 20 25 30 Experimental temperature! 35 40 FIGURE 5. Comparison of the frequency of firing of 4 repeating units recorded from the tentacular nerve from two 5° C-acclimated snails and two 25° C-acclimated snails. DISCUSSION Littorina littorea is capable of coping with both long-term and short-term changes in environmental temperature. In the present investigation this capability is expressed by a shift in the temperature of heat coma as a r
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. HEAT EFFECTS ON A MARINE SNAIL 343 90 80 70 ^60 £50 - X 20 10 '}25°C. o I I I I 05 10 15 20 25 30 Experimental temperature! 35 40 FIGURE 5. Comparison of the frequency of firing of 4 repeating units recorded from the tentacular nerve from two 5° C-acclimated snails and two 25° C-acclimated snails. DISCUSSION Littorina littorea is capable of coping with both long-term and short-term changes in environmental temperature. In the present investigation this capability is expressed by a shift in the temperature of heat coma as a result of laboratory acclimation to different temperatures. Fraenkel (1968) found that Littorina littorea apparently has little ability to adapt seasonally in regard to lethal temperature, and a shift of only about 1° C was found for the same species as a result of temperature acclimation in the labora- tory in the present study. It is difficult to imagine any adaptive significance in such a small shift in lethal temperature. However, L. littorea spends much of its time out of water and is exposed to a much greater range of temperatures than are organisms which show seasonal shifts in lethal temperatures, , fish (Prosser, 1973). The ecological significance of any given "lethal temperature" for a species depends upon whether or not the animal may be exposed to this temperature long enough to be killed or injured to the point where it might fall easy prey to some predator or disease, or suffer damage to the reproductive tissues. It is quite likely that L. littorea may survive body temperatures of over 30° C for a period of several hours on hot summer days. Maximum snail body temperatures recorded in the field are usually lower than the maximum tolerated in laboratory tests (Markel, 1971). It is reasonable to suppose that in intertidal snails the lethal temperature(s) might be set at the genetic limit for the species, and if this limit were sufficiently high in
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
