. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 1900 2100 2300 0100 Time. 25 U °_ 20 o 3 | a I 15 10 -" Time Figure 5. Changes in body temperature (mean ± SEM) of 5 specimens of Hemigrapsus midiis (solid line) in the intertidal zone. Crabs were released during a falling tide and monitored until the following high tide. Seawater temperatures (dotted line, solid symbols) and air temperatures (dashed line, open symbols! were also recorded during this time. Times of emersion and immersion of the crabs, as well as low tide (LT). are indicated on the graphs. Recordings wer
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 1900 2100 2300 0100 Time. 25 U °_ 20 o 3 | a I 15 10 -" Time Figure 5. Changes in body temperature (mean ± SEM) of 5 specimens of Hemigrapsus midiis (solid line) in the intertidal zone. Crabs were released during a falling tide and monitored until the following high tide. Seawater temperatures (dotted line, solid symbols) and air temperatures (dashed line, open symbols! were also recorded during this time. Times of emersion and immersion of the crabs, as well as low tide (LT). are indicated on the graphs. Recordings were made on (al 8 July 2001. when surrounding air temperatures were lower than ambient seawater tempera- tures and (b) 23 July 2001. when air temperature was higher than seawater temperature. from 11 °C in the morning to 22-24 °C by early afternoon. Despite this 12 °C rise in air temperature, the body temper- atures of the crabs did not change as rapidly, and reached only ± °C by the end of exposure period in air. The change in body temperature was similar to the observed increase in seawater temperature during the day (Fig. 5b). When the crabs were re-immersed, their body temperatures quickly equilibrated with the seawater. Discussion The observed rates of change in body temperature (Fig. 2) were similar to those reported previously for Hemigrapsus nudus (Greenaway et al., 1996). In lobsters, heat loss in air is more rapid than heat gain (Whiteley el 1995): this was also observed here for H. muhts (Fig. 2), probably due to the evaporative heat loss in air. During these experiments, sev- eral of the crabs regurgitated frothed fluids from the stom- ach, smeared this over the ventral carapace with the chelae, and raised their body above the substrate. This foaming behavior has been reported for a number of crab species (Lindeberg, 1980; Maitland. 1990) and can used to reduce body temperature (Jansen, 1970). However, there was no evidence to suggest that the H
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
