The lair of the honeycomb worm

It was a perfect afternoon for beachcombing: the weather was warm and sunny, the tide was right out and I walked barefoot along the shoreline. I found a beautiful jelly fish, some crabs and a few clams to add to the supper table. I was spoilt for choice for blips but decided to show this more unusual form of marine life which can easily be overlooked by the casual passer-by.

The honeycomb worm, Sabellaria alveolata, is a small marine creature that lives in a tube it constructs from sand grains glued together with its own mucus. The extraordinary thing about them is that they form vast colonies by attaching to rocks close to the lower tideline, which gradually turn into a huge hummocks composed of massed tubes. These reefs take on a rounded and curvaceous forms which themselves provide shelter for other marine species. At a glance the reefs look like boulders but if you stop to examine them (see LARGE) you will notice that they are composed of a mass of fragile sand-tubes, each one ending in a open aperture through which the worm inside can feed on floating particles filtered from the water when the reef is submerged.

Honeycomb worm reefs are found in the southwest of Britain but mainly in warmer climes such as the Mediterranean. They are vulnerable to disturbance (such as trampling) and cold weather but in optimum conditions they last for 10 years or so. Children and dogs were running around the beach today having a lot of fun but I don't think anyone else took any notice of these curious honeycombs.