I just can’t resist the big spring tides we had around the turn of the month. It’s a rare chance to get right down the beach and look at some of the animals and other organisms that normally only those folk who dive get to see.
What I was really after were sea anemones. As I wandered down the beach at Norwick, a large number of dog whelks were waiting out the tide in cool damp crevices, many on top of acorn barnacles of which they are a major predator.
Nearby was a topshell, probably a grey topshell. Now I’m old enough to remember spinning tops which resemble the shape of these conical-shaped marine snails. When the outer part of the shell becomes worn, the next layer down displays a wonderful mother-of-pearl effect. As with many of these gastropods, they have a calcareous “door” with which they can close off the entrance to the shell.
I had to go quite a long way down the shore until at last I came to some red beadlet anemones, the commonest species on rocky shores. All but one was by now out of water and therefore closed up, resembling jelly-like blobs. But in one small rock pool I was delighted to find one still open, its tentacles raised ready to catch any passing morsel of food such as prawns, worms or small fish – perhaps a bit ambitious until the tide turned. Once ensnared in the tentacles, the anemone stings its prey before pushing it into the central stomach and closing up while it is digested. Attached to the rock by a basal disc, these creatures can detach and move around for a better place and will even sting their neighbours if they feel threatened.
But what this one displayed beautifully was part of the ring of 24 blue spots or beadlets at the base of the tentacles from which these animals get their name – a real treat.