Field Reports

Saturday 24 July 2021   Rock Pooling at Felpham

Leader Jenny Etienne


We were so lucky with the weather! After a tremendous thunderstorm the night before and more rain forecast for the day after, we hit a dry ‘sweet spot’. With the tide receding and very pleasant weather conditions, ten members set off to the rapidly appearing pools bearing a variety of Chi Nats ki, reference books etc.  

Jenny introduced us to the rock pools, in the Upper Chalk beds, and described how the occurrence of plant and animal species is partially influenced by the time spent out of water. Seaweed also exist in chromatic zones, with red, brown and green species generally living at increasingly shallower depths. We found Sea Lettuce, Thong Weed, Irish Moss, Gut-weed, Saw Wrack and a Ceramium seaweed (which the group suggested should have the common name of ‘Brain Weed’!) See photo of specimens in a tray.

Common Prawn, Shrimp, young fish and both Hermit Crab (see photo of one in a Periwinkle shell) and Shore Crab were found together with various Periwinkle species (one of which was making a long track), Topshell and the familiar Limpet and Acorn Barnacle. We learnt that Limpets create their own, precisely sized, indents on the rocks that they find their way back to following their own mucus trail. There were several halves of Piddock shells. These are clam like shellfish which spend their lives burrowing into soft rocks such as clay and sandstone. Their long oval shells are wing shaped, giving them the common name of Angelwings. They also glow in the dark!

Earlier, we had seen an abundance of Beadlet Anemone and the hunt was on for the Snakelocks Anemone, a species which does not retract its tentacles and tends to stay in rock pools lower down the beach. A cry from Jenny brought us all scurrying, she’d found one! (see photo) What a beautiful creature. The green parts are composed of single celled algae which have a symbiotic relationship with the anemone, the algae producing energy through photosynthesis within the protection of the stinging tentacles.

Another extraordinary looking species was the Sand Mason Worm, some seen in ‘forest-like’ arrangements. These are a burrowing worm with a characteristic tube consisting of cemented sand grains with a fringe of tentacles at the top (see photo). One great surprise was to find a rarely seen (female) Masked Crab (see photo) and another to be shown the fossilized remains of Palm Trees from the Eocene Period, in the London Clay Beds (thank you Bruce and Tony respectively).

Not so surprising were the ever present Herring Gull and Black-headed Gull at the water’s edge together with Great Black-backed Gull and Common Gull which were also spotted.

Many thanks go to Jenny and her friend, Val (who provided some great equipment) for their expertise and to all attendees for their enthusiasm and ‘eagle eyes’ as well as their friendly company. (Oh, and to Chris for his photography!)

Gill Hance

A selection of seaweed

The splendid Snake Lock Anemone

The Sand Mason Worm


Masked Crab


A fossilised Tree Palm


A sunny afternoon for ChiNATS members on Felpham beach.

Chichester, West Sussex

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