Sex and size affecting time allocations for activities in Uca annulipes (H. Milne Edwards, 1837)

Abstract

We investigated the amount of time that large and small, male and female fiddler crabs Uca annulipes (H. Milne Edwards, 1837) spent on feeding, walking, standing, grooming, burrowing, inside burrows, fighting, and courtship waving. We video-recorded the activities of 45 males (22 small and 23 large), and 39 females (19 small and 20 large) each for 5 min, and calculated the percentage of time spent on each activity/crab. Our results showed that both sexes spent more time on feeding than on other activities. Males spent more time on building burrows, walking, and grooming than females, and females spent more time inside burrows than males. Smaller males spent more time on feeding, and less time on building burrows and on waving than larger ones. There were no relations between female body size and activities. Feeding rate/feeding claw was higher in males than in females, and crab body size was negatively associated with feeding rate/min. RÉSUMÉNous avons étudié le temps que passent les mâles et les femelles du crabe violoniste Uca annulipes (H. Milne Edwards, 1837) pour l'alimentation, la marche, le repos, la toilette, le creusement du terrier, le temps passé à l'intérieur du terrier, les combats et la parade. Nous avons enregistré en vidéo les activités de 45 mâles (22 petits and 23 grands), et 39 femelles (19 petites et 20 grandes) chacun pendant 5 min, et nous avons calculé le pourcentage de temps passé à chaque activité/crabe. Nos résultats ont montré que les deux sexes passent plus de temps pour se nourrir que pour toutes les autres activités. Les mâles passent plus de temps à bâtir des terriers, marcher et faire leur toilette que les femelles, et les femelles passent plus de temps à l'intérieur des terriers que les mâles. Les mâles plus petits passent plus de temps à s'alimenter et moins de temps à construire des terriers et à la parade nuptiale que les mâles plus grands. Il n'y a pas de relation entre la taille du corps de la femelle et ses activités. Le rapport taux d'alimentation/longueur de la pince servant à la prise de nourriture était plus élevé chez les mâles que chez les femelles, et la taille du corps du crabe était associé négativement au rapport taux d'alimentation/min.

Size‐dependent mating preference of the male fiddler crab Austruca perplexa

“…Male fiddler crabs wave slowly when the intensity of competition is low, females are small, and when females come very near and show their mating choice (Reading & Backwell, ; Tina, ; Tina et al, ). However, though small males spend less time and energy on courting females, they spend more time on feeding (Callander et al, ; Tina et al, ), perhaps because greater investment in feeding increases their growth rate and future reproductive success (Hasaba et al, ; Muramatsu, ; Tejedo, ). Once they grow in size, they will be preferred by females and will have a greater chance to acquire mates and maximize their reproductive fitness.…”

“…However, though small males spend less time and energy on courting females, they spend more time on feeding (Callander et al, 2012;Tina et al, 2016c), perhaps because greater investment in feeding increases their growth rate and future reproductive success (Hasaba et al, 2015;Muramatsu, 2010;Tejedo, 1992). Once they grow in size, they will be preferred by females and will have a greater chance to acquire mates and maximize their reproductive fitness.…”

Time allocations for different activities in the fiddler crab Tubuca rosea (Tweedie, 1937) (Brachyura, Ocypodidae)

“…Fiddler crabs are an excellent model for studying time allocations as they are highly social animals and show numerous social behaviours (Caravello and Cameron 1991;Weis and Weis 2004;Tina et al 2016). Moreover, their behaviours can be easily observed and recorded under natural conditions (Mokhlesi et al 2011;Tina et al 2016). Until now, only two studies investigated the effects of sex and size on time allocation in Leptuca panacea Novak & Salmon, 1974 andA.…”

“…Until now, only two studies investigated the effects of sex and size on time allocation in Leptuca panacea Novak & Salmon, 1974 andA. annulipes (Caraello andCameron 1991;Tina et al 2016). Both of these species are underground mating species in where males build the breeding burrows, and females select males based on their burrow qualities and incubate eggs inside those male burrows (Caravello and Cameron 1991;Backwell and Passmore 1996).…”

“…Males allocate more time than females for mate attraction and territorial defense. However, smaller-sized males are less attractive to females in many animals including fiddler crabs (e.g., mottled sculpin (Cottus bairdi (Girard, 1850)), striped triplefin (Forsterygion varium (Forster, 1801)), redlip blenny (Ophioblennius atlanticus (Valenciennes, 1836)), topi (Damaliscus lunatus (Burchell, 1823)), puku (Kobus vardoni Livingstone, 1857), and fiddler crabs Tubuca paradussumieri (Bott, 1973), Austruca annulipes (H. Milne Edwards, 1837), and Austruca mjoebergi (Rathbun, 1924)) (Brown 1981;Thompson 1986;Côte and Hunte 1989;Balmford et al 1992;Backwell and Passmore 1996;Jaroensutasinee and Jaroensutasinee 2003;Callander et al 2012), thus, they tend to spend less time on courtship displays (Tina et al 2016) as it increases the expenditure of time and energy without any benefit (Callander et al 2012). Furthermore, energy demand for gamete production is different between males and females.…”