The Comprehensive Marine Biodiversity Survey team found at least eight knobbly sea stars on the lowest reaches of Pulau Sekudu yesterday, by or just beyond the water's edge on the southern rim of a sloping flat. These were old, sprawling creatures with long arms, faded hues and an excess of tubercles on their central discs. We turned over the asteroids and scanned their ventral surfaces for hanger-ons such as brittle stars, scale worms and eulimids, a group of minute snails that attach themselves to echinoderms, before placing them in small pools to sit out the tide and a passing downpour.
The massive sea stars continued their slow hunt for benthic epifauna, but most of the other creatures we encountered on the boulders, rubble and seagrass beds of this rocky islet met their doom in slim vials, clear bags and deep buckets. Their eventual demise, in jars of alcohol or tubes of formaldehyde, serves a dual purpose: to give taxonomists the means to determine the animals' exact identity, for a cursory visual inspection more often than not fails to detect small but significant differences in genital or cephalic morphology that separate members of a complex clade, and chart the richness of habitats whose natural wealth risks being overruled by minds that recognise only the costs of missed opportunities.
The substratum on Sekudu, an uneven mix of coarse sand and broken rubble, is rather less amenable to yabby pumping than Chek Jawa's loose sediments. Here, the alpheids dwell in holes lined by large pebbles, which impede their capture despite vigorous attempts at sucking out the contents of promising burrows. We snagged just two snapping shrimp: a small, faintly striped thing about an inch long and a far larger, near-crayfish sized beast with a pale yellow carapace. The sieves also yielded numerous venus clams, assorted polychaetes, a few, probably commensal, gobies that failed to scoot deep quickly enough, and the restless wisp of a ghost shrimp that just betrayed its thalassinid proportions to the naked eye.
Handwork was somewhat more fruitful: the team bagged a cake star, a couple of Astropecten, a crown sea star, ball sea cucumbers, gaudy cucumariids and several pencil urchins, along with white and black temnopleurids with nereidid associates curled around their mouths. The echinoderms put up little resistance, unlike the crabs, which darted off to weedy retreats or raised their spiny claws from stony corners. Portunus pelagicus occured in overwhelming abundance, but we concentrated on two less common species, an orange and purple Charybdis that lurks in shallow overhangs and a robust swimmer with pale colours that lies half-buried in the silt. Also bagged were a thunder crab and random xanthids or pilumnids that wandered in view. Chitons, scale worms and a hoof-shield limpet turned up on the shells of Pinna and Placuna. Tube worms, soft corals, unknown actiniarians and a leaf porter crab that gave itself away by swimming against the current also joined the pail array before the surveyors, sogged and sagging with the weight of still-living specimens, bundled up a creaking ladder onto a low bumboat, leaving the island, consumed by a lingering mist, to a waiting line of herons and the sad, sweet calls of waders in twilight.
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