To casual visitors, the lower reaches of Changi offer little more than a murky sheet of water between a reclaimed beach and a barren straits. But when the tide swings the other way a little more strongly than usual, the shoreline dips to reveal a gentle slope of fine sediment blanketed by gelatinous stems and the shoots of littoral grasses. Tongues of sand puncture the flats, forming at their expanded bases a series of shallow, leaky basins that confine the creatures of the sea in ephemeral pools of silt, forcing crabs, fish and shrimp to seek shelter in beds dominated by simple, spoon-shaped leaves and a few fern-like blades.
The intertidal vegetation share the strand with animals that root for a living. Erectile sea pens, tiny towers of pale tissue and transparent polyps, sprout like wild asparagus from firmer substrates; small sea anemones, nubs of jelly the size of a nail, form part of the interstitial community; their larger cousins, occupying pits that offer other creatures questionable respite from danger, attain the diameter of undulating plates with countless spokes of stubby, sticky tentacles. There are also actiniarians with little more than monikers and a few half-familiar features: the so-called tiger anemone sports striking armbands and what appear to be red-tipped verrucae on its outer body wall; another nameless beast with a ring of yellow to brown tentacles attaches its petal disc to fan shells and window-pane clams, while minute columns ride roughshod on the shells of whelks and hermit crabs.
The remains of cockles, clams and hammer oysters litter the shore or adorn the tests of living sea urchins, betraying the slow, stubborn and ultimately successful efforts of moon snails, noble volutes and predatory sea stars to unearth and unhinge edible deposits. It's likely that many of these bivalves occur in staggering densities a mere foot or so below the surface, where they suck in organic particles and exhale with relief at every passive bid to elude the feet of fellow shellfish.
Changi is also home to a population of Placuna and Pinna; the former sidesteps the surf by offering minimal resistance to the waves, while the latter's sturdy halves, half-buried in life and set a loose in death, serve as handy footholds for sea anemones as well as small, pink-red cucumarids. Two species occur in abundance here, one armed with flimsy thorns and the other afflicted with bumpy warts, and both are fond of choice spots high in the water column on which they can extend their oral appendages to reel in the pick of the planktonic soup. Most other holothurians, being the ecological equivalent of large, marine earthworms, prefer to stick it in, embedding their sausage-shaped bodies in the sediment with just their rude ends in sight, save Phyllophorus which puts forth a conspicious ring of branched tentacles that could be mistaken for more potent arms.
The most prominent echinoderms here are the sea urchins, in particular Salmacis, the vain naiad who seldom grazes without a cloak of shells, leaves and debris to hide her true face and mask a prickly demeanour. Living specimens creep about in loose herds that vie with fan shells for the privilege of ruining bare feet. Sharing similar sartorial habits but rather less common than the white lady is another temnopleurid with dark spines and exuberant rows of brightly tipped tube feet that convey the impression of a pulsing globe. Meanwhile, laganids in a gaudy hue glide through the grains to imbibe select detritus with no inkling of what it's worth to live in a land where sentences by laity and legal eagles alike often make no sense.
Changi is no stronghold for asteroids, but the shore still harbours the odd Protoreaster as well as a sprinkling of armoured confections and spiny sand stars. The latter, though paper thin, are covered with miniature pillars or paxillae that lubricate, as it were, the animals' passage through loose grains. The other stars, which dwell in the open, are defended by flexible plates and in a few species, prehensile pedicellariae. Their most visible soft parts are the tube feet that protrude from the ambulacral grooves, but individuals completely immersed and in a state of repose extrude a battery of respiratory papulae from their aboral surface. These transparent, finger-like extensions of the animals' soft parts instantly withdraw when touched, but the outfit, though close-fitting and equipped with a safety valve, is far from being watertight. It's a hint too subtle that the group has few exaptations for life on land and prolonged exposure to air, be it on an exposed bank or in the hands of eager beachcombers, will result in a hydrostatic crisis of stellar proportions and death by suffercation.
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