Lateral compression is a disadvantage on gentle strands where the sand threatens to swamp and suffocate every form of substance and there is a perpetual struggle for dominance between the grass and the grains. The vegetation, which prize gaining ground over bushy heights, wrestle with the sediment, binding the silt with roots and shoots and infusing the layers beneath with the surplus of the sun. Like giant, marine earthworms, holothurians grub within the dunes, displacing nutrients as they burrow and enriching the seabed with their own fertile discharges. Other invertebrates, though protected by shells, spines or stinging chaeta, plunge into the sand to carve hollows of security for themselves, from which they feed on fresh deposits or extend a siphon or pinnate mouthparts to sup from the water column. This underworld of clams, worms, sand dollars and even stranger bodies, which rivals the visible portions of the flat in numbers and productivity, also nourish those of pelagic origins that have adapted to life benthic.
Two migrations occur in the life of a typical pleuronectiform. One begins when young animals abandon the currents to seek a lower level of survival on muddy bottoms and sandy beds. The other, somewhat concurrent, journey involves a reconfiguration of cranial structures and the fish's plane of existence: one eye creeps upward until it lies adjacent to the other, while the abandoned flank loses its pigments and assumes a position of inferiority as the flounder, sole, halibut or tonguefish, having lost its internal bouyancy, settles on the flat to earn a living on the side.
Large-toothed flounders tend to be sinistral or left-handed, while soles, which may have separate or conjoined marginal fins, are dextral, lying on their former left quarters. Both families are adept burrowers, using their fins and vigorous body undulations to vanish under a coat of fine silt with little more than their eyes exposed. The former, however, often rests in the open, assured perhaps that their specks and blotches match the surrounding substrate and court indifference from most visual predators. Crypsis also probably aids in prey capture and the intertidal regions of Changi, where these flatfish are not infrequently sighted, offer a feast of smaller fish, worms, shrimp and free-swimming shellfish that'd fit their jaws and fail to note the presence of a fatal slip.
Sit, suck and swallow is a strategy that accomodates a multiplicity of bauplans and demersal niches. In rather less plain patches of coarse sand and multihued rubble, flatheads hunt in such comfort they evacuate only when a very narrow perimeter of tolerance is breached. The fish erupt with some force and speed they offer little trace of their trajectories, which may be mere feet away from their original spot. Even post-larval specimens, such as this boldly marked hunter at Beting Bronok, employ this tactic to evade attention in minute tide pools, which they share with nervous gobies and nonchalant shrimp that will one day graduate from the status of companions to cuisine.
Platycephalids have strongly built skulls that tend towards depression and end in reptilian jaws with a gape that probably far exceeds that of a comparably sized flatfish. Victims are inhaled whole and gripped by auxilliary teeth before ingestion, and probably suffer their fate as a result of nothing more than being at the wrong place at the wrong time. Other scorpaeniforms, notably the true stonefishes (Synanceini), are known to nudge the odds in their favour by welding lures that bring hungry fish within reach. It's not clear, though, if Trachycephalus uranoscopus, a small and innocuous, relatively speaking, member of the nominally lethal tribe, brandishes such bait. Bearing a pout that recalls that of a stargazer, this waspfish apes the ability of its namesake to sink out of sight, baring only a slim barrage of teeth at foe and food alike.
A predator with adaptations that can be commandeered for foraging as well as defence, the numbfish is a ray that shocks rather than stings. Local narcines, which differ from their sister group the torpedinids by their rounded, as opposed to truncate, anterior margins, probably deliver little more than a buzz to human fingers, though the voltage ought to be sufficient to zap marine creatures in its weight class and allow the sluggish batoids to overcome far swifter prey. Torpediniforms are thought to be the most primitive members of their group, as the fish still possess fairly typical hindquarters beyond the pectoral disc. But the apomorphy of paired electrical organs in the head region has possibly contributed to the order's persistence in a world of deadlier rays.
Small numbfish are occasionally spotted at Changi, where they glide over the submerged portions of the beach to scan for choice morsels. Somewhat larger whiptail rays also prowl the area, cruising in the shallow pools where their sandy tones offer scant contrast against the sediment. In these and other more 'advanced' rays, danger is held at bay by one or more caudal spines. Sustenance is acquired purely through mechanical means; the broad fins are used to unearth buried clams and polychaetes, which are crushed and consumed by inferior jaws. For this and most other flatfishes, the upper reaches of the sea, where sunlight meets an infinite lightness of beings, offer little but bleak possibilities compared to the soft, succulent pickings of continental shoals that run deep and dark until they plunge into a barren land.
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