The fondness of familiar land snails for garden foliage and overbred flowers is perhaps why gastropods are seldom ranked highly on the food web and get little respect from fans of big game. On the seabed, however, a heavy shell and snail's pace offer fewer hurdles to good hunting in an environment where many other creatures live in even slower lanes, lie under the false security of sand and silt or sit tight on rocks and broken rubble. Speed is hardly a concern when survival hinges on outrunning a sluggish pack or an evolutionary arms race that pits chemists against civil engineers who must resist corrosive assaults or the broad feet of hungry juggernauts.
Betraying man's penchant for according begrudging respect to things that can heal, thrill or kill, cone snails are among the few gastropods that have captured popular imagination and sowed fear of god in the hearts of reef visitors. Conids, including one associated with human fatalities, have been recorded in local waters and are known to inhabit intertidal depths, but the mixed blessing of nocturnal activity and uncrossed paths in recent years has reduce these venomous snails to living legends or broken shells on the shingle of resort islands.
A different family of marine snails that superficially resemble the sneaky harpooners can still be found at reasonable frequencies on local shores. Where there is clean sand and lush seagrasses, a meandering line through the substrate is likely to lead one to an olive snail as it ploughs through the sediment for carrion or small prey. Though sharing with conids a long, narrow aperture with a modest spire and shells with similar patterns and gloss, olivids are harmless molluscs whose porcelain beauty compels aesthetic conchologists to savour them dead and dry. The living animals are far more entertaining, though; as snails go, they are speedsters that reveal only a glimpse of their soft parts before the entire snail sinks beneath the surface with the poise of a submarine mole. Like some burrowing slugs, the 'head' is shaped like a shield or veil, serving perhaps to help bulldoze the snail through loose grains. Eyes are absent or minuscule, and a long siphon protrudes into the water column to create a slim trail that give the game away in exposed flats.
The moon snails are another family of fossorial predators. With bodies that outshine the olivids in expansiveness and near-globular shells that have aroused comparisons with breasts and balls, naticids patrol the seabed for other shellfish, which they overpower and consume with sensuous haste. Some have even been observed turning the tables on a subphylum of mollusc feeders, though such scenes are probably scarce locally as soldier crabs are all but gone from mainland strands. Dining as they do on sundry bivalves and slower snails, naticids still occur in reasonable numbers at shores such Changi and Chek Jawa, where females betray the aftermath of penetrative trysts with stiff collars of sand or mud. Elsewhere in the region, the snails have inspired more playful instincts, in odd games of chance whereby their shells are used as counters or piled up to draw bets on whether their number is even or not.
Moon snails rely on a combination of brute force and alchemy to reach their victims' vulnerable portions. Volutes dispense with such finesse altogether, having the bulk to simply envelop prey in a muscular foot and rasp their way through shell and stubborn carapace. Their size is also their downfall, unfortunately, as noble volutes and baler shells more often than not end up in the cooking pots of gourmands who cannot imagine the logic of turning down seafood that costs not a penny. Dead shells usurped by hermit crabs are not infrequently seen at still-healthy shores, though, suggesting that some populations lurk in depths beyond the reach of starving beach apes, where they face instead the existential threat of regular apocalpyses that dig up the snails and their non-planktonic brood amid a relentless effort to tame the sea and domesticate the forces of nature.
Still, life finds a way. Even by coasts where the waters have been pushed away and held back by walls and steely wills, the animals return to their former haunts whenever the dredgings cease and the currents send a fresh stream of veligers to recolonise barren sand. But the sighting of a live Tonna dolium on a beach lost to most and left to its own devices many moons ago was nonetheless welcome, for it hinted at richer communities in the littoral zone of a reclaimed land. What little is known about tun snails is that they favour seagrass meadows and readily dig down into the substrate to hide as well as hunt holothurians, which are paralysed prior to being swallowed whole. Crustaceans and even fish are said to be fair game for some of the family, which in turn risk falling prey to cousins with a taste for fellow shellfish. It's likely that most tonnids raid mudflats too deep for tidepooling, so the sight of one envenomating and engulfing a sea cucumber remains a grail restricted to divers who forsake the reefs for the muck of benthic serendipities.
Like tonnids, cassids specialise in devouring echinoderms, though their choice of food is pricklier and abundant enough in the shallows to permit occasional encounters with these pretty snails. Helmet snails have rather more sculptured shells than tonnids, with prominent lips around the aperture and a short, dorsally recurved anterior notch that houses the siphon, a snorkel-like organ used to suck in fresh water as well as the scent of sand dollars. Three species are known in Singapore and as luck, or the insane drive to land on local patch reefs hours before daybreak, would have it, two have been spotted on banks where clypeasteroids abound and even caught in the act of conspicuous consumption. To feed, the snails squirt neurotoxic saliva that immobilises the spines before inserting their snout through the urchin's anal orifice or any other convenient hole to rasp out the palatable bits. It's a habit that invites less fascination than the bloodier antics of charismatic megapredators and leaves no lasting impression on the minds of beachcombers who come across the hollows of tests with little value to an economy limited in sense and reduced to dollars.
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