Rocky II

After our last rockpooling adventure, there was definitely some keenness to do it again. However, the main challenge at this time of year is finding a date; you need a good low tide (ie a spring, rather than a neap, tide) which falls within daylight hours, ideally not at dawn, and preferably at the weekend. Well, three weekends ago fitted those criteria with low tide at Birling Gap at 2.45pm, sundown just before 4pm, and the water went down to 1.1m above Chart Datum (ie the lowest it can practically go down to).

Unfortunately, lots of the usual suspects from Forest Row couldn’t make it for various reasons, and it looked like it was going to be just me and Rachel slowly keying things out by ourselves. We’d just started on our first top shell when Evan joined us, having come over from Eastbourne, and shortly after that Graeme turned up too, so we had quite a strong complement of expertise. As is usual, I ended up looking for seaweeds, and everyone else went hunting animals, which involved lots of turning over of big rocks.

Picture of people rockpooling

Looking for marine species. Photo: Evan Jones

The first of the species that were less familiar was the Common Chiton (Lepidochitona cinerea), a small mollusc that is rather flat and tightly attached to the rock.

Picture of Common Chiton (Lepidochitona cinerea)

Common Chiton (Lepidochitona cinerea)

Another very different mollusc was the Common Piddock (Pholas dactylus), the shell of which was found by Evan (I think). These animals bore into the rock and are thereby protected from the wave action, and they are also phosphorescent.

Picture of Common Piddock (Pholas dactylus)

Common Piddock (Pholas dactylus)

One of the reasons I enjoy looking at the seashore is that you can find animals from phyla that are either exclusively or overwhelmingly marine, so have evolved what appears to us terrestrial species to be unusual life forms. One such group are the anemones, and we found quite a few of them, ranging from the common and familiar Beadlet Anemone (Actinia equina), through to the Strawberry Anemone (Actinia fragacea), Dahlia Anemone (Urticina felina) and Sagartia troglodytes.

Picture of Sagartia troglodytes

Sagartia troglodytes

I was still nosing around looking at the seaweeds, though the others found the longest, wriggliest animal of the day, a Common Ragworm (Perinereis cultrifera). This is in the phylum Annelida, the segmented worms, which also includes the earthworms.

Picture of Common Ragworm (Perinereis cultrifera)

Common Ragworm (Perinereis cultrifera)

It was also nice to find a couple of species from the marine phylum Echinodermata, the Common Starfish (Asterias rubens) and Green Sea Urchin (Psammechinus miliaris), the latter being a species which doesn’t appear to have been recorded at Birling Gap before, though it isn’t rare.

Picture of Green Sea Urchin (Psammechinus miliaris)

Green Sea Urchin (Psammechinus miliaris)

Crabs were relatively few in number, though we saw several Shore Crab (Carcinus maenas) and one rather splendid Broad-clawed Porcelain Crab (Porcellana platycheles).

Picture of Shore Crab (Carcinus maenas)

Shore Crab (Carcinus maenas)

Evan also pointed out one of the smaller barnacles on the lower shore; this was the one named Elminius modestus by Darwin, that great barnacle expert, though it is now named Austrominius modestus. It is native to Australasia, though is now established in north-west Europe. Unusually for a barnacle in British waters, it is comprised of four rather than six plates.

Picture of Austrominius modestus

Austrominius modestus

Graeme also found a tiny wee bivalve, which was a Marbled Crenella (Modiolarca tumida), a species he’d not seen before (and such things are relatively few and far between these days).

One other interesting find was this Cretaceous (c 85 million year old) fossil sea urchin, which is probably Hemiaster morrisii, first described by Lewes-based Gideon Mantell in 1822 (though he called it something else). It was exposed in the chalk and was gradually being eroded by the sea, so I extracted it using my mushroom knife.

Picture of Hemiaster morrisii

Hemiaster morrisii?

Finally, I totted up the seaweeds I’d managed to identify, and there were twenty, plus a Ceramium:

  • Ahnfeltia plicata
  • Blidingia marginata
  • Chondrus crispus
  • Cladophora sericea
  • Cladostephus spongiosus
  • Corallina officinalis
  • Dilsea carnosa
  • Fucus serratus
  • Furcellaria lumbricalis
  • Gelidium pusillum
  • Gracilaria gracilis
  • Hildenbrandia sp
  • Mastocarpus stellatus
  • Osmundea pinnatifida
  • Plocamium cartilagineum
  • Polysiphonia fucoides
  • Rhodothamniella floridula
  • Ulva intestinalis
  • Ulva lactuca

and the rather splendid little hydroid animal, Dynamena pumila. We’ll have to go back again in the spring.

Picture of Polysiphonia fucoides

Polysiphonia fucoides

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