Field guide

These are the groups I look for. They aren't species-level identifications, just enough to know what you're looking at and how to behave around it.

Seagrasses

Flowering plants, not seaweeds: they have roots, flowers and seeds. Singapore has a dozen or so species, from tape seagrass, whose ribbons can grow longer than your arm, to spoon seagrass, whose small paired oval leaves are easy to miss. Seagrass meadows shelter young fish and are grazed by dugongs and turtles. When the tide is out, walk on the bare sand between patches.

Sea stars

The big knobbly sea star, with dark knobs on its upper side, is the one people remember from Chek Jawa. Sand stars are flatter and bury themselves, leaving a star-shaped dent. Sea stars breathe through their skin, so leave them in the water.

Sea anemones

Relatives of corals and jellyfish, catching food with stinging tentacles. Carpet anemones can be sticky to the touch and some sting, so don't touch them. Some anemones host small shrimps or crabs that live among the tentacles. Tube anemones pull back into a buried tube when disturbed.

Crabs

Everywhere, from the mangrove mud to the reef edge. Male fiddler crabs wave one oversized claw. Swimming crabs have paddle-shaped back legs and can pinch hard. Hermit crabs live in empty snail shells, which is one more reason never to take shells home.

Snails and other molluscs

Moon snails plough through sand and drill neat holes in clam shells. Their eggs are laid in a rubbery "sand collar". On rocks you'll find nerites, limpets and periwinkles holding on through the dry hours.

Nudibranchs

Sea slugs without shells, often tiny and often brightly coloured. Many carry a frilly plume of gills on their back and a pair of feelers at the front. They're delicate and easily washed off their food, so look and move on.

Hard corals

Singapore's waters are cloudy, yet its reefs have a surprising variety of corals. On the lowest tides, reef flats at the southern islands come out of the water. Corals are animals that host algae in their tissues, and they bleach when the sea stays too warm for too long. Never step on or touch them.

Sea cucumbers

Slow relatives of sea stars that sift sand and mud for food and clean the sediment as they go. Some defend themselves by releasing sticky threads, so don't squeeze or lift them.