British Marine Life Study Society

by John Hayes
(Dorset Heritage Coast Warden)
I'd spent the day on the cliff top working on the coast path on one of the hottest days of the year so far. Below me was a sea as flat as a table top, a chequerboard of boulder ridges and sandy furrows clearly visible between the kelps and plumes of Japweed. Two cormorants take turns to surface dive while another dries off, wings extended, on the wreck of the old coal barge.

Under Water

Work finished, I go down to the beach and scramble over the boulders to escape the crowds. A welcome surge of cool water beneath my wet suit and another world unfolds. It is murky as I slide over the smooth boulders and slimy seaweeds on the submerged lower middle shore, but I only have to swim out a little further for the visibility to improve. Clumps of Cystoseira, tipped with blue luminescence sway to and fro with the currents. A Corkwing Wrasse, Crenilabrus melops, about 12 cm sees me and dives for cover.

Limpets and Sea Anemones

A large Limpet, Patella vulgata, green seaweed clinging to the top of its conical shell, is on a near vertical rock face walking on its muscular pink foot. I reach down towards it but it clamps down tightly on the rock face before I even touch it. Snakelocks Anemones, Anemonia viridis, are everywhere, most clinging to rocks but some on kelp fronds. All are the grey form, not all have purple tips, hundreds of wavy stinging tentacles searching for food. I offer on finger, it feels as though it is being gently scratched. Brown globular sea squirts approximately 5 cm high and 3 cm across have attached themselves to some seaweeds and are filtering out food from the sea water.

Red Stalked Eyes

Pushing the Japweed, Sargassum muticum, out from my path, the rock ridges and seaweeds give way to a patch of sand. Two Netted Dogwhelks, Hinia reticulatus, are migrating across the patch leaving trails in the sand as they go. Perhaps they can 'smell' some rotting delicacy up ahead.

 A streak of silver flashes by me on the right. And another. and another. Six Grey Mullet, Chelon labrosus, the largest about 30 cm long, swim off into the murk. I come across a rock crevice and peer down into it. Two cream and brown pincers are clutching at a Limpet - a Velvet Swimming Crab, Necora puber, - is it trying to prise the Limpet off? The red stalked eyes see me, daring me to come nearer - no thanks, I'm quite close enough! The crab is magnificent, cream and brown hairs, purple lines down its legs, red luminescence between its joints and its not going to back off. We stare at each other for a couple of minutes, its powerful pincers outstretched, then slowly it tires of me and sinks down amongst the crevice seaweeds.

   Velvet Swimming Crab

Silvery Shoal

I move off and swim off further. the depth is now about 3 metres. suddenly a shoal of around 100 to 150 fish appears below me, each about 4 cm long. I have never seen anything like this before. their backs glint blue-green as they catch the sunlight. I find as I swim above them I can 'herd' them until suddenly in synchronised unison they outwit me by changing direction. I follow them for a few minutes, but I do not want to, over disturb them, and my head is beginning to get cold, so I swim back to the shore.


This description is from a snorkel on 27 July 1995. It was a neap tide, almost fully out and about to turn. I swam out just west of the old coal barge at Bran Point (Grid ref: SY 743 814). Access to the beach was at the slipway at Osmington Mills.
John Hayes is a Dorset County Council Heritage Coast Ranger.

Rockpooling at Osmington Mills

Diverse Reports  (SCUBA Diving)

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