There are no coral reefs on this, and possibly any, side of Pulau Ubin, a meandering, muddled, messy shore of holiday chalets, broken fences and wayward rocks. The waters here, churned by the blades of freightened vessels and enriched by the waste of rivers from a damaged peninsula, are too dark and estuarine for scleractinians, save patches of Oulastrea, whose shallow chalices threaten, but fail, to overwhelm low slabs that rise from a station of improvenance
In place of skeletal colonies, these slopes present a landscape of extremes: soft expanses of mud and unusually robust spoon seagrass which tempt, tantalise and taunt top-heavy waders with glimpses of life and gooey regrets, and rising in between these alluvial traps, heaps of granite that litter the coast with deep grey edifices, whose sharp edges are untempered by a periostracum of slime, shells and deranged sea slaters. Astride these boulders are other, miniature, peaks: the honeycombs of volcano barnacles, dense nubbins of Balanus, the gentle cones of limpets true, false and hoofed, and muricids with coils embellished by knobs, ridges and spikes – the drills occupy the trophic cracks between slower, or sedentary, feeders and crabs that emerge after dark to probe, poke and pry open shells with lines of weakness or broken apertures. To maintain their ranks against the depredations of Ozius and Menippe, the snails interrupt their sortees with gatherings in sheltered enclaves, where they produce rows of capsules that fade from light yellow to Tyrian blue as their contents seethe with planktonic feet.
Violet crabs with short, hooked toes and pulmonates that have traded their shells for tougher skins scrape the surface of the rocks for edible filaments, the former relying on speed and the latter on sloth for concealment. Also barely discernible on a wall of organic coatings is Aquilonastra coronata, a sea star which shuns trawling depths. Formerly placed in the circumglobal grabbag genus Asterina but now regarded as members of a clade peculiar to the northern Indo-Pacific, these intertidal asteroids exhibit a spectrum of colours that range from "mottled olive-green" to fawn and "bright rust-red", with brown, red or black markings. The aboral plates of these little asterinids are studded with numerous paxillae resembling radiating digits, amid which stubby papulae, the respiratory processes of this class of echinoderms, can be seen when the animal is submerged. More tuft than tower, the paxillae, though much shorter than those in astropectinids and bearing two distinct forms of spinelets (the hallmark of the species), may aid in defence or offer a measure of passive resistance to silt, while small pedicellariae, which are said to be present, probably take action against larger settlers.
Orange specimens pop up not infrequently, suggesting that this morph enjoys no great selective disadvantage compared to its mottled counterparts on a terrain riddled with gaudy encrustations. On the lower reaches of the rocks, a zone that seldom, if ever, suffers prolonged exposure, grow ascidians solitary and colonial, gaudy polyps and lurid sponges – the poriferans and lone tunicates confront the air with stiff bearings, while softer bodies hang limply from slippery faces as they sit out a tidal pause to their routine. For all its maligned dullness, the straits between Changi and Pulau Ubin is a productive strip. Cells in suspension and nutrients from fringing woods and fertile wastelands may stain this ditch, but creatures that can stomach thickened soups and sift out the babies from the bathwater thrive in this emulsion, growing, branching, lolling and spreading their bulk over favourable perches to capture a traffic of fine particles. Tricked by shallow abundance, gorgonians, sea cucumbers, tube worms and feather stars have invaded these flats, drawing in their wake an entourage of ophiuroids, cowries, shrimp and porcelain crabs. The filter feeders also attract attention of a less desirable note, in the form of flatworms and slugs that sup on sessile prey.
There is enough in these waters to feed a menagerie of warmer things. Vulnerable outcrops provide nesting sites for black-naped terns, which paint their roosts with the pale remains of anchovies and other small pelagic fish that have fattened themselves on floating carapaces. Herons rest on handy buoys and the frames of tethered farms. White-bellied sea eagles issue hollow challenges before they bed down on trees with threadbare crowns. From the thickets below, hogs trot out at last light to feast on the beach, where salty fruit, swollen figures and decaying food arrive with each tide to return the favour of the land. And over the sliver of sand between the woods and the wetness, long green dragonflies, hunters from a largely crepuscular family, dart from the shadows to patrol the edges of an island whose heart has been hollowed out to build a city that shines but whose veins, though torn and battered, still throb with the bodies of a fairer age.
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