Anemones and urchins, and learning to look without lifting a stone

Hands behind the back

The first rule I learnt as a child on a very different coast was to turn stones over to see what was underneath. The first rule I teach anyone who comes out with me now is the opposite. Arrive at a pool, crouch at its edge with your hands behind your back and your shadow off the water, and look for a full minute before doing anything else. Nearly everything I have written about in this notebook was seen in that first minute, or in the second, once the pool had forgotten I was there.

Shadows matter more than noise. A shadow falling across a pool sends small fish and shrimps under the rim at once, and they take several minutes to come back out. On the east-facing ledges in the morning, that means approaching from the south or north and crouching low, not standing over the water with the sun at your back. A polarising pair of sunglasses cuts the surface glare and is the only piece of equipment I would call essential.

If I do need to look under something, it is a loose stone small enough to lift with one hand, lifted slowly, looked under for as long as it takes to count to twenty, and put back exactly as it was, the same side up and the same way round. The underside of a stone is a different world from the top, with its own sponges, worms and crabs that die if they are left facing the sun. On a busy ledge in summer, I have stopped lifting anything at all, because enough people are already doing it.

The anemones

The anemone I see most often is the beadlet, a smooth dark red dome the size of a thumbnail when closed and a small crown of red tentacles when open underwater, with a ring of bright blue spots around its top edge if you look closely. It sits on vertical rock faces just below the waterline and in almost every pool that holds water through a calm morning. Out of water it pulls itself into a blob of red jelly that people step over without noticing.

The other common one is the snakelocks, which cannot close and always looks like a mop of long waving tentacles, grey-brown or green, often with purple tips. The green colour comes from algae living inside the tentacles, so snakelocks crowd into the sunniest, shallowest parts of a pool. Its sting is stronger than the beadlet's and can be felt on the thin skin of a wrist, which is one more reason for the hands-behind-the-back habit.

Black urchin or purple urchin

Two sea urchins are common in the shallows here, and they are easy to confuse until you know the one thing that separates them. The black urchin is a deep glossy black all over, with long, sharp spines, and it lives on bare rock in the most wave-beaten places. Its underside, if you ever see one washed up, has a large soft area around the mouth. The purple urchin is more variable, from dark violet to olive to brown, with slightly shorter spines, and it tends to cover itself with bits of shell, pebble and seaweed held on by its tube feet.

That habit of decorating itself is the easiest field mark. If an urchin is carrying debris on its back, it is almost always the purple one. If it is bare, glossy and very black, sitting on a wave-washed ledge, it is the black one. The purple urchin is also the one collected for eating in winter, which is regulated with closed seasons, and it has become noticeably scarcer on the more accessible ledges near towns over the four winters I have been counting.

Counting instead of collecting

Every winter since 2021 I have counted urchins along the same two ledges, one on the Maresme and one in the Garraf, on the calmest morning I can find in January. I count within a strip roughly two metres wide from the waterline out, walking the same line each year and marking black and purple separately. The numbers are too small and too rough to prove anything, but they are mine and they are consistent.

On the Garraf ledge, which is harder to reach, the purple count has stayed roughly level. On the Maresme ledge, a short walk from a station, it has fallen by more than half, while the black urchins on the same ledge have held steady. I cannot say why for certain, but the pattern matches what longer surveys along this coast have reported, and it is one reason this notebook never describes exactly where the better pools are.