St John's on the rocks

Sea anemones greeted the night with expanded discs. The fairly common yet poorly known Phymanthus anemones with their frilly tentacles resembling an external network of arteries place themselves in cozy nooks by rocky substrates, where they can whoosh in so fast and deep that they are near impossible to extricate. They come in many colour morphs, from a uniform green to stripey shades and red highlights., but are thought to be variations on a single species. There was also a small carpet anemone (Stichodactyla gigantea) that harboured a lone shrimp. In somewhat deeper crevices we also found colonies of what appear to be small anemones or large corallimorphs with white-tipped tentacles. 

There are crab spiders and there are spider crabs. Both groups conjure visions of spindly limbs that dangle from a squat pearshaped body. Though the former are greatly feared, none have yet managed to wrangle a scream to match one that erupted from an inflight collision between my duck and a legful of this. The family Majidae contains both the largest (see a specimen at the RMBR) as well as some of the tiniest crabs known. In Singapore waters, the smallest known crab is a similar-looking coral dweller, but this little spider crab with a carapace just over half a cm wide and pretending to be a piece of dirt on the fronds of a seaweed comes pretty close.

Much larger but no less visible to the lazy naked eye is the velcro crab (Camposcia retusa), a species of spider crab with hairs and hooks on its body that trap debris and algae. The animal actually 'plants' sponges and ascidians on its back to render itself indistinguishable from the surrounding sessile growth on the coral rubble. Moving about at a snail's pace helps prevent the crab from giving the game away, but what happens when it changes its skin? Does it gingerly undrape itself of its spineless accessories before it sheds its exoskeleton and reassembles its gaudy bling? Or do the hapless colonisers lose their mount at every moult?