Locomotor activity of the fiddler crab, Uca subcylindrica (Stimpson), under artificial illumination
Circadian, Fiddler crabs, Locomotor rhythm, Uca subcylindrica
Biological Rhythm Research
Specimens of the fiddler crab Uca subcylindrica (Stimpson) were captured in south Texas (USA) for locomotor rhythm studies. Actographic data were analyzed using Tau™ sofware. Under constant illumination (LL) and darkness (DD), the semiter-restrial crabs express a circadian rhythm of locomotion. When exposed to illumination/darkness cycles (LD12:12 or LD14:10), their bouts of activity are entrained to the photoperiod. In LD, activity is generally bimodal with an initial burst about 0.5 h after illumination. A second burst of activity begins 1 to 2h before the end of illumination. When transferred from LD to LL, a locomotor rhythm with an average period of 24.6 ± 1.0h (n = 19) is expressed in 89 percent of the crabs. On the other hand, when placed in DD after LD (n = 8), the crabs are either arrythmic or weakly rhythmic (period = 23.8 ± 0.2h; n = 2). If the onset of illumination is advanced by 6h, a period of less than 24.0h is detected in the actogram. If the onset of illumination is delayed by 6h, a locomotor rhythm with a period greater than 24.0h appears. The locomotor behavior of this species of fiddler crab, Uca subcylindrica, is not related to the tidal rhythmicities seen in other members of the genus Uca. Rather, it has strong circadian components.
Original Publication Date
DOI of published version
Thurman, C. L. and Broghammer, A. M., "Locomotor activity of the fiddler crab, Uca subcylindrica (Stimpson), under artificial illumination" (2001). Faculty Publications. 3592.