We met at Lihou Causeway in drizzle which had turned to warm sun by the time we left the beach. We went along the first bit of the causeway then turned to the South where there are big tidal lagoons with gravel bottoms and occasional rocks. Most of the animals we found were under these rocks. Many of them had been turned and not replaced by ormer gatherers over the last few spring tides so were less rich in species than they would be later in the year.

Some of the Section on the beach at the edge of a lagoon.

Under the rocks was the beautiful blue sponge Terpiops fugax.

Terpiops fugax

Also there were several species of crabs, Young Chancre (Cancer pagurus), Shore Crab (Carcinus maenas), the fierce Lady Crab (Velvet Swimming Crab) (Neocora puber), Smooth and Hairy Porcelain Crabs (Pisidia longicornis and Porcellana platycheles).

Shore crab (Carcinus maenas) with eggs.

And the Cushion Star Asterina gibbosa

Cushion Star

Also under a rock we found the large gravel tube, c. 20mm across, of the filter-feeding worm Chaetopterus variopedatus, though we did not have the heart to remove the worm from its tube.

Tube of Chaetopterus

Under one of the rocks was a group of the sea slug Aeolidea papillosa. These feed on sea anemones and transport the stinging cells of the anemone to the tips of their cerrata (outgrowths on their backs) to use in their own defence.

Aeolidea papillosa

The top of the rocks were covered with a rich variety of sea weeds. We found many interesting animals here including the striped flatworm Prostheceraeus vittatus

Prostheceraeus vittatus

Also the large Sea Lemon (Archidoris pseudargus) a sea slug.

Sea Lemon

Walking across the bottom of the lagoon, looking like mobile seaweed, we found the inoffensive brown spider-crab Pisa tetraodon

Pisa tetraodon

As we left the beach we noted large numbers of the Thick Top Shell (Osilinus lineatus).

Thick Top Shell

We looked at the differences between three common species of top shells as seen in the next photograph. Osilinus lineatus on the left, the non-British Gibbula pennanti in the middle and the Flat Top Shell Gibbula umbilicalis on the right. The last two are very similar but Gibbula umbilicalis has an umbiliculus (the hole up the middle of the shell) and usually occurs slightly higher up the beach than G. pennanti.

Three Top Shell species