transitory prezoeal stage. Hyman found the first 

 two zoeal stages most abundant at the surface, the 

 third probably at intermediate depths, and the 

 fourth and fifth zoeae usually on the bottom. He 

 found the zoeal stages to last collectively about a 

 month. 



The megalops, a single stage lasting nearly a 

 month, is a powerful swimmer. At the end of 

 this stage the animal retires to cover of some sort, 

 molts through two relatively weak crab stages and 

 at last emerges as an active small crab measuring 

 about 2 mm. across the carapace. 



Feeding movements in U. pugilator are essenti- 

 ally the same as in the other two species of Uca 

 and are discussed in the account for U. pugnax. 

 Schwartz and Safir (1915) found the males moved 

 the small cheliped to the mouth 28 to 46 times per 

 minute, and females 61 to 92 times, when actively 

 feeding on small particles in sand. Teal (1958) 

 found that this species may wander into tide pools 

 and shallow creeks to feed underwater at low 

 tide. Miller (1961) considered U. pugilator to be 

 the most specialized in mouth parts among Caro- 

 linian TJcas and well adapted to feeding on coarse 

 substrate such as protected sandy beaches. 



In experiments on salinity tolerance, Teal 

 (1958) found that in fresh water 50 percent of U . 

 pugilator died after 3.5 days. In water of 7 °/ 00 

 more than 50 percent of the animals survived a 

 10-day test. Given a choice of fresh or 30 

 7 00 sea water, U. pugUator chose salt water, 

 but preferences shown by females were less strong 

 than those shown by males, as was true also of 

 U.*pugnax. Teal concluded that this species lies 

 between U. minax and U. pugnax in its tolerance 

 of fresh water and can survive soakings of the 

 Salicornia marsh with rain between spring tides. 



Given a choice of sand or mud substrate above 

 or underwater, U. pugilator burrowed almost ex- 

 clusively in sand above water level. When either 

 of the other species of Uca was present as a com- 

 petitor for space, there was a reduction of 50 

 percent in the number of burrows that U. pugila- 

 tor dug in sand above water. In tanks where 

 there was no favorable substratum of sand above 

 water, its behavior was not changed by presence 

 of another species. When restricted to an unfavor- 

 able, low, muddy marsh, U. pugilator did not sur- 

 vive. Teal conjectured that this species cannot 

 feed properly where sand is absent. 



Respiration rates for this species are higher 

 underwater than in air (Teal, 1959), probably 

 due to increased activity necessary to ventilate the 

 gills. 



Teal (1958) found that temperatures of 45° C. 

 on open sand flats of the Salicornia-Distichlis 

 marsh in Georgia prevent U. pugilator from 

 permanently occupying these areas, though they 

 do feed there in cooler parts of the year. In gen- 

 eral, temperatures experienced in nature were not 

 considered a limiting factor. Orr (1955) found 

 that U. pugilator died in 81 minutes at 40° C, in 

 18 minutes at 41° C, in 9 minutes at 43° C. and 

 in a little less than 9 minutes at 46° C. Demeusy 

 (1957), investigating respiratory rates in popula- 

 tions of this species from Florida and Massa- 

 chusetts, found that the northern population had 

 a higher rate of metabolism at low temperatures 

 (1.4° C.) than the Florida population, but that at 

 15° C. the difference was not significant, Demeusy 

 found the northern population less sensitive to 

 temperature change and more resistant to low 

 temperature than the Florida population. On the 

 other hand, Edwards (1950) found metabolic dif- 

 ferences in these populations at 20° C. Teal 

 (1959) found that above 25° C. specimens from 

 Georgia showed no adjustment of respiration for 

 temperature acclimation, but that below 20° C. 

 there was some evidence of acclimation though 

 not so well developed as in U. pugnax. Vemberg 

 (1959) pointed out that metabolic activity in Uca 

 of the temperate zone exhibits a seasonal cycle 

 and that this cyclic change must be taken into ac- 

 count in comparing physiologic activity of rela- 

 tives at different latitudes. Moreover, he stated 

 that metabolic response of fiddler crabs has real 

 significance in their distribution. 



Crane (1943) gave a detailed description of the 

 display and breeding relationships for this spe- 

 cies. Display of males starts with the body ele- 

 vated, cheliped tips lowered, and the meral-carpal 

 joint of the major cheliped elevated. The cheliped 

 is then extended up and out, the crab at the same 

 time raising to tiptoe. The cheliped is held out 

 for an instant, then smoothly returned to the orig- 

 inal position. The minor chela makes weak cor- 

 responding gestures and fingers of both chelae 

 are nearly closed throughout. Waves are made at 

 a rate of about one per second. At moments of 



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