The larger sea anemones, notably the medusae that populate the flats with pretty shrimp and clownish pets, are hard to miss, being plate-sized slabs of tissue and sticky tentacles that present a swirl of colours amid waters of green and grey. Many other actinarians, however are less showy and seldom turn up in lazier lines of sights. A number even occupy what are possibly the highest reaches of their phylum, settling on rocks that receive only faint sprays of seawater and rare moments of tidal flooding.
In these zones that swing between drenched and drained dwell sea anemones in the genus Anthopleura. Some of these little brown blobs can occur in densities that cause confusion with zoanthids, which prefer softer substrates and live as colonies joined at the foot. Appearing as nothing more than "shiny bumps on hard surfaces" to most tidepoolers, these small anemones have prospered with a strategy of feast and famine made possible by a life of simple needs and snug requirements. A few feed for the most part on the lightness of being captured by cells within their skin. Both these and their azooxanthellate kin, however, will not refuse passing supplements of protein snared by an armoury of stings. One solitary species, Anthopleura buddemeieri, even manages to waylay the swift-legged things that scurry about intertidal pools and survives in low numbers on the rare rocky fringes of Singapore's southern shores, where competition is scarce for high spots and hot seats beyond the reach of the waves.
Grainier shoals harbour their own retinue of polyps that dig into the silt, exposing only their oral disc and a circlet of tentacles. Burrowing anemones in the genus Peachia present a dull kaleidoscope of glassy arms with brown-grey chevrons, the visible iceberg of a pale tube with faint lines. The animals are not uncommon on the slopes of Changi and Tanah Merah, where they risk the thud of feet aware of little else on these flats that run rife with creeping snails, hermit crabs and transparent shrimp.
The adults probably feed on careless pelagics or blundering members of the shallow benthos. Juveniles in the genus are known to play a different game, hitching a ride on floating bells and hewing away at the gut contents and, later, the gonads of their hosts. Consumed from the inside, the jellyfish would drift to the edge of the sea or dash itself on damp ground, giving its tormentors a final lift to the surf zone before they hit the sand and hide between the beads.
Comments