Birling Gap

Birling Gap, view west
Birling Gap, view west

The shore at Birling Gap is typical for Sussex. Dominating the area is an extensive intertidal wave-cut chalk platform with extensive tabular flint which is located beneath undefended chalk cliffs. Shallow gullies scoured and extend down the shore. A narrow, up to 20m, graded fringing shingle bank extended from the cliff margin to the exposed chalk with occasional chalk boulders from cliff falls. The initial exposed chalk was littered with chalk boulders and cobbles, with pieces of exposed flint. Small shallow pools are present (these dry out in summer on spring tides). Algal cover is virtually absent; no fucoids here. However, the boulders can be lightly covered in chains of diatoms forming short fine filaments and the green alga, Ulva prolifera. The small pools contain very short Corallina officinalis plants. A few winkles, Littorina littorea and L. neritoides. The bare rock contains the fine tubes of Polydora ciliata which occur, borrowing in the chalk, down the shore and together with piddocks, Pholas dactylus, and limpets, Patella vulgata, contribute to biogenic chalk erosion.

View towards the cliffs
View towards the cliffs

Some 5m further down the platform occasional Patella vulgata can be found these increase in numbers, not high, further down the shore. Some sand trapped in pools hosted sand mason worms, Lanice concheliga. The tabular flint is colonised by barnacles, notably juveniles during February-May, Austrominius modestus (syn. Elminius modestus). A second zone is encountered with the scattered presence of Osmundea pinnatifida, pepper dulse and wracks, notably Fucus vesiculosus, bladder wrack, and F. serratus, saw wrack. This zone merges to a third with more algal cover (virtually all of the exposed chalk), dominantly O. pinnatifida and F. serratus (depending on the time of year), but also some Rhodothamniella floridula, sand binder, (sand-trapping species; acts like marram grass on dunes). A few stunted Fucus vesiculosus and serratus were present. Pools contain tops shells: Gibbula cineraria and G. umbilicalis, Osilinus lineatus, Beadlet anemones, Actinia equina are scarce. The shallow gullies host the usual range of crustacea and molluscs. Beneath flint cobbles and other hard objects chitons, scale worms, seamats, brittle stars, infrequently the anemone, Sagartia troglodytes, can be found.

View down wave-cut platform
View down wave-cut platform

Species List

Dynamena pumila Zig-zag hydroid
Actinia equina Beadlet anemone
Sagartia troglodytes An anemone

Polydora ciliata A spionid, boring worm
Sabellaria spinulosa A sand tube worm
Lanice conchilega Sand mason worm
Pomatoceros lamarcki A keelworm
Harmathöe imbricata A scale worm
Nereis pelagica/em> A ragworm

Elminius modestus Barnacle (4 plates)
Semibalanaus balanoides A barnacle
Sphaeroma serratum A stout, oval isopod
Idotea granulosa An elongate flat isopod
Palaemon elegans A prawn
Crangon crangon Brown shrimp
Pagurus bernhardus A hermit crab
Porcellana platycheles Broad-claw porcelain crab
Cancer pagurus Edible crab
Necora puber Velvet swimming crab
Carcinus maenas Shore crab

Lepidochitona cinerea A chiton
Acanthochitona crinitus A chiton
Acanthochitona fascicularis A chiton
Gibbula cineraria Grey topshell
Gibbula umbilicalis Purple or flat topshell
Patella vulgata Common limpet
Littorina fabalis Annual flat winkle
Littorina littorea Common winkle
Littorina saxatilis Rough winkle
Osilinus lineatus common topshell
Crepidula fornicata Slipper limpet
Nucella lapillus Dog whelk
Buccinum undatum Common whelk
Mytilus edulis Common mussel
Ostrea edulis Native oyster
Cerastoderma edule Common cockle
Venerupis senegalensis Pullet carpet shell
Hiatella arctica Wrinkled rock borer
Pholas dactylus Common piddock
Barnea parva Little piddock

Membranipora membranacea Sea mat
Electra pilosa Frosty sea mat
Alcyonidium gelatinosum A gelatinous encrusting seamat
Cryptosula pallasiana A hard encrusting seamat
Bryozoa indet crusts Unidentified encrusting seamats

Amphipholis squamata A brittle star
Asterias rubens Common starfish

Lipophrys pholis Shanny
Pomatoschistus microps Common goby

Gelidium pusillum Creeping straggle alga
Palmaria palmata Dulse
Rhodothamniella floridula Red sand collector
Phymatolithon purpureum A pink paint weed
Lithophylum incrustans A pink paint weed
Corallina officinalis A calcified alga
Cystoclonium purpureum Purple claw weed
Furcellaria lumbricalis Clawed fork weed
Chondrus crispus Carrageen / Irish Moss
Dichtyota dichotoma Brown fan weed
Ceramium sp. Banded pincer weed(s)
Ceramium deslongchampsii A claw weed
Plumaria plumosaSoft feather weed
Polysiphonia sp. Siphon weeds
Osmundea pinnatifida Pepper dulse
Fucus serratus Saw wrack
Fucus vesiculosus Bladder wrack
Ectocarpus sp. Fine hair weed
Ulva lactuca Sea lettuce
Ulva prolifera Proliferous gut weed
Cladophora rupestris Green hair algae
Bryopsis plumosa Mossy feather weed
Bryopsis hypernoides Mossy feather weed
Derbesia mirina Silky thread weed