This month the Rockpool Project is focussing on some of our coastline’s most colourful and diverse inhabitants- the sea slugs. In my internship with the Rockpool Project I’ve been looking at some of the iNaturalist data our fantastic volunteers and participants have helped collect.

This report will take you through an overview of all 140 species of sea slug that have been found around the UK coast, starting with the most common species recorded on iNaturalist and getting rarer the further down the table you get.

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!

Let us know which sea slugs are most common where you are, and which ones surprised you in our list.

All photos are clickable to view photo ownership.

Photo Common Name Latin Name Number of Observations
Spotted Seahare Aplysia punctata 554
Crowned Aeolis Facelina auriculata 431
Orange-clubbed Sea Slug Limacia clavigera 337
Sea Lemon Archidoris pseudoargus 334
Pink Coryphella Edmundsella pedata 322
Sap-sucking Slug Elysia viridis 285
Four-lined Polycera Polycera quadrilineata 283
NA Polycera kernowensis 240
Side-gilled Seaslug Berthella plumula 229
Velvet Dorid Jorunna tomentosa 206
Angular Seaslug Okenia nodosa 196
Boston Facelina Facelina bostoniensis 187
crested aeolis Antiopella cristata 185
NA Diaphorodoris luteocincta 163
NA Aeolidia filomenae 151
barnacle-eating dorid Onchidoris bilamellata 150
Hairy Spiny Dorid Acanthodoris pilosa 146
White Aeolis Favorinus branchialis 134
NA Doto pinnatifida 121
NA Doto fragilis 120
NA Crimora papillata 111
Striped Fjordia Coryphella lineata 107
Winged Thecacera Thecacera pennigera 101
NA Aeolidiella alderi 84
NA Candiella lineata 81
NA Rostanga rubra 79
NA Diaphorodoris alba 78
NA Tenellia cuanensis 78
Venus Seaslug Okenia elegans 75
whip fan nudibranch Candiella odhneri 75
NA Facelina annulicornis 73
Humped Ancula Sea Slug Ancula gibbosa 72
NA Favorinus blianus 65
NA Geitodoris planata 65
NA Eubranchus farrani 61
NA Polycera norvegica 60
NA Eubranchus linensis 60
NA Palio nothus 59
citrine nudibranch Pelagella castanea 57
NA Polycera faeroensis 51
NA Discodoris rosi 46
NA Trapania tartanella 45
NA Doto cuspidata 43
NA Eubranchus viriola 42
NA Pruvotfolia pselliotes 41
Celtic Sea Slug Onchidella celtica 40
Slender Eolis Coryphella gracilis 40
Homberg’s Triton Tritonia hombergii 38
White Atlantic Cadlina Cadlina laevis 38
NA Aeolidiella glauca 36
NA Eubranchus vittatus 36
Gaudy Babakina Babakina anadoni 33
NA Lomanotus marmoratus 33
Branched Sapsucker Placida dendritica 32
Johnston’s balloon eolis Tergipes tergipes 32
NA Aegires punctilucens 32
Crimson Hermaea Hermaea bifida 32
NA Trapania lineata 30
club-gilled nudibranch Eubranchus pallidus 29
NA Spurilla neapolitana 28
Neat Aeolid Cuthonella concinna 28
NA Rubramoena rubescens 28
Fuzzy Onchidoris Onchidoris muricata 27
Warty Doris Doris verrucosa 25
Three-coloured Aeolis Eubranchus tricolor 24
NA Lomanotus genei 24
NA Atalodoris pictoni 24
NA Doris berghi 24
NA Tenellia foliata 23
Minute Aeolis Eubranchus exiguus 22
NA Rubramoena amoena 22
NA Atalodoris pusilla 22
Crowned Seaslug Doto coronata 21
NA Coryphella browni 19
Shag-rug Nudibranch Aeolidia papillosa 18
NA Tenellia aurantia 18
Rough Side-gilled Seaslug Pleurobranchus membranaceus 17
NA Hancockia uncinata 17
NA Dendronotus keatleyae 17
NA Capellinia fustifera 16
NA Janolus hyalinus 15
NA Trapania maculata 15
NA Doto dunnei 13
NA Cadlina pellucida 13
NA Okenia aspersa 12
NA Doto tuberculata 12
NA Doto floridicola 11
Red-gilled Nudibranch Carronella pellucida 11
NA Candiella plebeia 11
NA Doto millbayana 10
NA Jorunna artsdatabankia 10
NA Coryphella chriskaugei 10
NA Doto koenneckeri 9
NA Doto lemchei 9
NA Facelina vicina 9
Beaumont’s Aeolid Cumanotus beaumonti 8
NA Doto hystrix 8
Tuberculate Dorid Adalaria proxima 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
Embleton’s Aeolis Embletonia pulchra 4
NA Dendronotus lacteus 4
Depilatory Seahare Aplysia depilans 3
NA Calma gobioophaga 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
NA Doto onusta 3
Rim-backed Nudibranch Palio dubia 2
Ridged Acteon Limapontia senestra 2
NA Doto maculata 2
NA Doto sarsiae 2
NA Thordisa azmanii 2
NA Dendronotus europaeus 2
NA Okenia pulchella 2
Spotted Lagoon Aeolid Tenellia adspersa 1
Black Limapontia Limapontia capitata 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