RESPIRATORY METABOLISM OF THE FIDDLER CRAB UCA PUGILATOR FROM TWO DIFFERENT LATITUDINAL POPULATIONS

¹ Biological Laboratories, Harvard University, Cambridge, Massachusetts

Determinations of the respiratory rates of Uca pugilator from two different latitudes (Woods Hole and Florida) have been made at 1.4° and 15° C.

1. Woods Hole Uca pugilator show a higher rate of metabolism at low temperature than do specimens of the more southerly populations.

2. Uca pugilator from the higher latitude are less sensitive to temperature changes than Uca pugilator of same weight from a southern latitude. This has been shown by a lower Q₁₀ for the Woods Hole population.

3. Woods Hole Uca are more resistant to low temperature than Florida Uca.

4. The same experiments made after the animals have been left at a common temperature of 20° C., show that a stay of seven or eight weeks under similar conditions does not abolish the metabolic differences observed between populations.

5. These physiological characteristics and some morphological ones might be used to distinguish two subspecies of Uca pugilator.