Vol. 60, 2021
Plasticity of Foraging Strategies Adopted by the Painted Ghost Crab, Ocypode gaudichaudii, in Response to in situ Food Resource Manipulation Experiments
Lab, Natural Sciences and Science Education, NIE, Nanyang Technological
University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore.
*Correspondence: E-mail: firstname.lastname@example.org;
Received 28 February 2020 / Accepted 19 April 2021
The feeding strategies of Ocypode gaudichaudii
at two sandy beaches, Culebra Beach (CB) and Playa Venao (PV) in Panama
were studied via three experiments. Two separate manipulative in situ
experiments were conducted to determine how the densities of food
resources and the size of the supplemented food offered to the crabs
can affect their diet and food handling behavior. The third experiment,
a transplantation study was also conducted to determine the plasticity
of the feeding behavior of the displaced crabs. In the first
experiment, freshly-emerged crabs showed different feeding modes when
washed-sediment was seeded with different densities of diatoms and rove
beetles, which suggests that they are optimal foragers. Crabs hoarded
food in the second experiment when food augmentation using small and
large food pellets were placed around the burrows at the beginning and
end of the crabs’ feeding cycle. All freshly-emerged crabs from both
sites foraged on the small pellets outside their burrows and did not
cache food; when pellets were provided at the end of the feeding cycle,
crabs from CB fed on some of the small pellets and returned to their
burrows with the uneaten pellets left on the surface whereas crabs at
PV picked up all the small food pellets and transferred them into their
burrows over several trips before they plugged their burrow entrances.
Only the crabs from PV carried the large food pellets supplemented at
the start and end of the feeding cycle into their burrows. In contrast,
the crabs at CB often left behind the partially-eaten pellets on the
sand surface, probably due to the increased risk of predation
associated with the prolonged handling time of the large food pellets.
Excavation of the burrows of the crabs that hoarded food showed that
all the pellets were deposited at the bend of the burrows, indicating
that they were not consumed immediately. Crabs that fed in droves at PV
stopped droving and foraged around their burrows after being
transplanted to CB. This is the first documentation of food hoarding in
a sandy beach macroinvertebrate at a resource-impoverished habitat. The
plasticity of feeding strategies adopted by the painted ghost crab in
response to different densities of food resources in the habitat could
be an adaptation to the dynamic sandy beach environment.
Key words: Food caching, Functional response, Opportunistic scavenger, Optimal Foraging Theory, Transplantation experiment.
Citation: Yong AYP, Lim SSL. 2021. Plasticity of foraging strategies adopted by the painted ghost crab, Ocypode gaudichaudii, in response to in situ food resource manipulation experiments. Zool Stud 60:0kk. doi:-.