Like most common names, 'hairy crab' fails to convey much information beyond the notion that said brachyuran is somewhat hirsute and, hopefully, palatable when steamed and served with a tart sauce and spice. The odd 大闸蟹 has found its way to local beaches, victims no doubt of members of a salvation army dedicated to questionable accumulations of destiny, but these creatures, which require far cooler waters to fry their eggs, probably find such acts of goodwill way too hot to handle and perish in a barren state.
The hairy crab most familiar to intertidal explorers of local shores is a bumbling pile of legs attached to the scowl of a shell. Covered with bristles that gather dirt and trap sediment, these pilumnids pursue a life of deliberate movements on rocky outcrops and fringing rubble, where they subsist on seaweed, sponges, polychaetes and noxious polyps, the latter of which confer a measure of disagreeability to their mortal wounds. Many xanthid crabs, which have made a taxonomical break from pilumnids on account of fused male abdominal segments as well as distinguishing larval and genital traits, also appropriate the potent cocktails of toxic organisms and have evolved colours that discourage fatal sampling, but Pilumnus verspetillio appears to put more store in stealth than virulence and faced no selective pressures to ditch hair for hue.
The two families are not unjustifiably confusing and confused with each other, as many pilumnids hardly deserve their popular name and not a few xanthids are distinctively hirsute. One shaggy example with patches of setae in a vaguely concentric pattern on its carapace, spotted on the reef flat of St John's Island, was aptly identified as Actaeodes hirsutissimus. Despite its lumbering gait, the crab was quick on the uptake and scooted into a crack when it sensed a presence with foul intentions and the risk of getting into a pickle. Though described more than 180 years ago and distributed across the Indo-West Pacific, few details are available about this and other similar species save their prevalence in nearshore habitats throughout the region and a comparative study of larval features. So there is little to tell if local members of the subfamily Actaeinae occupy a distinct ecological niches from their pilumnid look-alikes and whether they face the same threats that confront the group on shores where the wild things truly are.
What is left of local reef flats, with their arcane heaps of growing layers and animal remains that refuse to bow to clinical expectations, presents a scene many urban environmentalists would regard as incompatible with a sanctioned vision of blue waters and clean seas. But it is here, at shores that have escaped burial by imported sand or reclaimed the lower reaches of artificial walls, that nature thrives without, or despite, the intentions of human nurture. Few dare to carouse or collect in the shadow of a naval base and an exclusive green, so the channel between Pulau Brani and the Serapong Golf Course has regained a quantum of the colonies that once guarded the island. As a result, staghorn and cauliflower corals, along with disc and soft corals, have returned with a vengeance, populating the flat with broad plates, overlapping laminae and branching columns.
Within the three-dimensional mazes of dendritic corals, where minute polyps line brittle arms and turn hard water into hidden places, dwell little clams, fat-headed gobies, gun-toting shrimp and belligerent crabs with no capability for adult survival beyond their growing homes. Even when the tide has fallen, the symbionts hold tight to their nooks, preferring to respire under pressure than risk lower pools. Two families of stout, strikingly marked crabs, Tetraliidae and Trapeziidae, have repeatedly squeezed themselves into this narrow niche. Another corallicolous crab, a fuzzy xanthid with slightly less fussy host requirements and baby blue eyes, has been recorded on Pocillopora, Acropora, Stylophora and Galaxea fascicularis, and is said to retreat to burrows near the base of the colony. The few I saw off the northeastern coast of Sentosa, however, were mired in complacency on the upper boughs and offered a rare opportunity to snap them with their backs to their world. Like its more colourful roommates, Cymo andreossyi performs housekeeping duties in its chosen domain, although it's not clear if these chores extend to joining the gang to nip at the feet of rampaging stars. There is, however, consensus that the richness of these communities is a sign that a reef, even one within sight of a container port and persistent city, has had time, space and benign neglect to restore its own health and recruit a diversity of creatures whose existence, after living adrift in the currents, would otherwise come to a sorry head.
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