Shells, spines and stings

Like the dozen well-armed policemen with three patrol cars and riot van at the carpark, the crepuscular citizens of Changi venture out in the darkness with a full set of armour and arsenal. Because you never know what you might be encountering for the very first, or last, time. For this noble volute, a trip to the shore could mean a one-way ticket into a pail and thereafter a pot. One of the larger species of marine snail found in local waters, Voluta nobilis is a predator of clams and other bivalves that failed to entomb themselves deeply enough in the sediment. With the patience of prophets, the volute engulfs the hapless valves with its ample body until the halves open for want of oxygen. I often come across their shells with anomuran occupiers but this was the first time I saw a live animal, with its striking black-and-yellow mantle and siphon. With luck, it won't be the last encounter with a duck for the snail, for its vivid flesh and that of its even rarer cousin the baler shell are sought after by souls tired of the usual molluscan fare of cockles and conches. You could say, everything can eat but eat everything liao, there will be nothing left to eat...   

A shell much less savoured in sauce is the moon snail, which like the volute is a hunter of fellow molluscs. The phantom forms of white-shelled Naticids are common on Changi, gliding over the grains with their mantle fully extended over a globose shell. Sometimes mistaken for a grotesque slug, their hard shell is revealed only when the animal is poked or probed by curious fingers, upon which it retreats into its mobile home and seals the aperture with a hard operculum to catch up on cable and change its facebook status. If forced to remain inside for too long, the snail is wont to suffocate, for the act of stuffing its immense body into the the compact shell involves the expulsion of much water. They much prefer to let it all hang out and plough their way through sand and silt in search of juicy flesh in hard packages. Unfortunate clams or button snails receive a ravenous embrace and an unwelcome drilling into their living room that allows the moon snail to plunge in and rasp the shell clean of all occupants. Besides the usual pale shadows, we found a bright orange individual this morning, which boasts cool racing stripes in white.   

Tiny button shells often fall prey to Naticids, and their vacated spirals are quickly claimed by puny hermit crabs with frilly antennae. The little anomurans are sadly little higher up the food chain, for these scavengers are heavily fed upon by swimming crabs, moon crabs, fish and larger shrimp. Those who grow out of collecting buttons move on to whelks and Naticids, and when the coast is clear, engage in petty thievery of mates, with the larger males grabbing onto the shells of females or skulking around a potential pair to steal a suit. 

With their prickly demeanour, sea urchins have far less turbulent love lives. In fact, it's debated whether they love life at all, for their spiny tests preclude mutual physical contact and allow only the remote meeting of gametes in mid-water. Pencil urchins with their thick, serrated spines come with a byzantine array of secondary spines, roving tube feet and stalked pedicellariae that probably can't reach far enough to remove the tube worms that have settled near the tips of the primary spikes.

In much greater numbers occur the white Salmacis urchins which graze in loose herds all over the shore. Many were sitting high and dry by the litter line, ruminating on their ill-luck in silence under a meagre cloak of seaweed. The rest assembled in illegal volumes to tempt fate with the crush of a bootie. Their complacent hubris and fashionable vanity fit their namesake, who turned his mythical back on chastity to ravish an unwilling nymph. 

With nowhere to go but down under, bizarre anemones spread their harpooned arms over the sand to ensnare blundering creatures. The most alien-looking of the night's lot, these cnidarians have a broad oral disc with a mouth bearing stripes that create the impression of fanged jaws. My duck decided against testing the pale ring of long tentacles, which look considerably more potent that the merely sticky stings of carpet anemones. It's probably wiser not to mess with a thing with the name of a wildflower but the biting humour of fair Charybdis...   

Comments

[Snail]

Marvellous photos!

[Aydin]

Very nice pictures of snails.

It is interesting that the moon snails can't seem to reduce their oxygen requirement when forced in to their shells.