For all their minute charisma and bead-eyed charm, fiddler crabs, which occur in multitudes in the mangroves and soft flats of warmer regions, occupy the lower ranks of the intertidal food chain; the ocypodids risk becoming crunchy morsels for shorebirds and reptiles during their frolics on the mud, and are sitting ducks for serpentine fish, larger decapods and even nemertean worms when they retreat to the bubbles of their inner chambers to sit out the flood tide.
Uca are deposit feeders, consuming organic particles and infaunal organisms by shoving a clawful of wet silt into their faces, sifting the fluid using specialised mouthparts and discarding a pellet of inedible portions. En masse, the crabs' feeding cum filtering activities, along with their digging and maintenance of burrows for shelter and sex, result in a regular churning of the upper layers of the sediment and infusions of oxygen that support the growth of associated plants. But three species of Uca, one of which can be found in abundance on the firmer reaches of Pulau Semakau's western shore, in particular the arched perimeters of trees that are reclaiming the beach after a century of human occupation, are known to wave off the textbooks and indulge in a little meat on the side.
As recorded in a population off the east coast of Africa, the crabs gave in to savage impulses on occasion, attacking small shrimp and eating the crustaceans alive, with males finding at last a chance to wield their primary chelae as tools for major destruction rather than mere signalling devices. Some have acquired a taste for their sand-bubbling cousins, while others pursue and pulverise smaller members of their own species. Competition for resources in a dense community has been touted as a possible cause for this habit, which runs counter to the norms of ucid society and points to the persistence of behavioural plasticity even in creatures adapted to benign regimes. Local porcelain fiddler crabs are off the hook so far, but it is certain that should they rock the boat, such insouciance to the established rules of conduct will offend the sensibilities of those who question the need to challenge the comfort zones of an air-conditioned society, who find thought an act too dim to be granted free rein, and who regard as intolerable the cheek to laugh at the law and reveal the faultlines of a land in search of prosperity but never quite at ease with progress.
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