This table will provide a quick run-down of all 140 species of sea slug that have been recorded from rockpools across the UK, and show you which are the most common. For this table we have used records from iNaturalist.

The sea slugs are some of our coastline’s most colourful and diverse inhabitants. What we have defined in this table as sea slugs is not an official taxonomic group but a collection of marine-living slug lineages you can find in the UK. The largest number of species in this table will belong to the nudibranchs- a group of solely carnvirous sea slugs. You will also see some sea hares, sap sucking slugs and the celtic sea slug featured as well.

While sea slugs actually evolved before land slugs, the celtic sea slug is from a lineage that evolved for land, but then adapted back to living at the coast, and breathes air!

As you take a browse, does any species surprise you? How common a sea slug species is can vary hugely dependent on your location in the UK. I was very surprised to see that a species that’s vary rare where I live in Falmouth, Edmundsella pedata- the pink coryphella nudibranch, is the 5th most common in the UK!

All photos are clickable to view photo ownership.

Check below the table for more information on our data sources

Photo Common Name Latin Name Number of Observations
Spotted Seahare Aplysia punctata 584
Crowned Aeolis Facelina auriculata 458
Orange-clubbed Sea Slug Limacia clavigera 361
Sea Lemon Archidoris pseudoargus 358
Pink Coryphella Edmundsella pedata 327
Four-lined Polycera Polycera quadrilineata 293
Sap-sucking Slug Elysia viridis 289
Side-gilled Seaslug Berthella plumula 246
NA Polycera kernowensis 240
Velvet Dorid Jorunna tomentosa 220
Angular Seaslug Okenia nodosa 213
crested aeolis Antiopella cristata 193
Boston Facelina Facelina bostoniensis 187
NA Aeolidia filomenae 184
NA Diaphorodoris luteocincta 163
barnacle-eating dorid Onchidoris bilamellata 159
Hairy Spiny Dorid Acanthodoris pilosa 157
White Aeolis Favorinus branchialis 137
NA Doto pinnatifida 127
NA Doto fragilis 122
Striped Fjordia Coryphella lineata 115
NA Crimora papillata 111
Winged Thecacera Thecacera pennigera 105
NA Aeolidiella alderi 89
NA Rostanga rubra 85
NA Tenellia cuanensis 84
NA Candiella lineata 81
NA Diaphorodoris alba 78
Venus Seaslug Okenia elegans 77
whip fan nudibranch Candiella odhneri 75
Humped Ancula Sea Slug Ancula gibbosa 74
NA Facelina annulicornis 74
NA Geitodoris planata 68
NA Favorinus blianus 66
NA Palio nothus 65
NA Eubranchus farrani 62
NA Polycera norvegica 62
NA Eubranchus linensis 61
citrine nudibranch Pelagella castanea 58
NA Polycera faeroensis 54
NA Gargamella rosi 47
NA Trapania tartanella 45
NA Aeolidiella glauca 44
Slender Eolis Coryphella gracilis 44
NA Doto cuspidata 43
Homberg’s Triton Tritonia hombergii 42
NA Pruvotfolia pselliotes 42
NA Eubranchus viriola 42
Celtic Sea Slug Onchidella celtica 41
Gaudy Babakina Babakina anadoni 39
White Atlantic Cadlina Cadlina laevis 39
NA Capellinia vittata 37
NA Spurilla neapolitana 36
NA Lomanotus marmoratus 34
Branched Sapsucker Placida dendritica 33
NA Aegires punctilucens 33
Crimson Hermaea Hermaea bifida 33
Fuzzy Onchidoris Onchidoris muricata 32
Johnston’s balloon eolis Tergipes tergipes 32
NA Trapania lineata 30
club-gilled nudibranch Eubranchus pallidus 29
Neat Aeolid Cuthonella concinna 28
NA Rubramoena rubescens 28
NA Atalodoris pictoni 28
NA Coryphella browni 26
Warty Doris Doris verrucosa 25
NA Doris berghi 25
Three-coloured Aeolis Eubranchus tricolor 24
NA Tenellia foliata 24
NA Lomanotus genei 24
NA Atalodoris pusilla 23
Minute Aeolis Eubranchus exiguus 22
NA Rubramoena amoena 22
Crowned Seaslug Doto coronata 21
Rough Side-gilled Seaslug Pleurobranchus membranaceus 21
Shag-rug Nudibranch Aeolidia papillosa 19
NA Dendronotus keatleyae 19
NA Tenellia aurantia 19
NA Hancockia uncinata 17
NA Capellinia fustifera 16
NA Janolus hyalinus 15
NA Trapania maculata 15
NA Doto dunnei 13
NA Cadlina pellucida 13
NA Candiella plebeia 13
NA Okenia aspersa 12
NA Doto tuberculata 12
NA Doto floridicola 11
NA Doto millbayana 11
Red-gilled Nudibranch Carronella pellucida 11
Embleton’s Aeolis Embletonia pulchra 10
NA Jorunna artsdatabankia 10
NA Coryphella chriskaugei 10
NA Doto koenneckeri 9
Tuberculate Dorid Adalaria proxima 9
NA Doto lemchei 9
NA Facelina vicina 9
Beaumont’s Aeolid Cumanotus beaumonti 8
NA Doto hystrix 8
NA Tenellia caerulea 7
NA Calma glaucoides 6
Flat Limapontia Limapontia depressa 6
NA Cuthona nana 6
NA Atagema gibba 6
Red-fingered Coryphella Coryphella verrucosa 6
Alder’s Seaslug Alderia modesta 5
NA Hero formosa 5
NA Atalodoris sparsa 5
NA Atalodoris oblonga 5
NA Eubranchus scintillans 5
NA Idaliadoris depressa 5
Green Aeolis Tenellia viridis 5
Bushy-backed Nudibranch Dendronotus frondosus 4
Salt-and-pepper Nudibranch Caloria elegans 4
NA Dendronotus lacteus 4
Depilatory Seahare Aplysia depilans 3
NA Calma gobioophaga 3
Ridged Acteon Limapontia senestra 3
NA Doto eireana 3
NA Hermaea variopicta 3
NA Tenellia pustulata 3
NA Doto hydrallmaniae 3
NA Doris sticta 3
NA Armina loveni 3
Rim-backed Nudibranch Palio dubia 2
Black Limapontia Limapontia capitata 2
NA Doto maculata 2
NA Doto onusta 2
NA Doto sarsiae 2
NA Thordisa azmanii 2
NA Dendronotus europaeus 2
NA Okenia pulchella 2
Spotted Lagoon Aeolid Tenellia adspersa 1
NA Okenia leachii 1
NA Aldisa zetlandica 1
NA Hermaea cantabra 1
NA Calliopaea bellula 1
NA Polycera elegans 1
NA Corambe testudinaria 1
NA Candiella manicata 1

Why only iNaturalist data? Though the National Biodiversity Newtwork (NBN) has records going back further, sea slugs are one of the most intensely recorded and verified marine groups on iNat. As such, we feel the iNaturalist data gives sufficient coverage of species over the UK to use solely for this.

Please note, numbers of each species recorded etc. will change from date of publication.