There are large differences in community and diversity of sea slugs across the UK. This document will guide you through the differences we see between all our 9 hubs, starting with some summary statistics on the numbers of species recorded at each hub area, then a map of the three most common species recorded there, and finally an appendices at the end to go through each hub’s species list in full detail if you really want to get into the nitty gritty

Take a look, you may be surprised how many species that you find often in Devon and Cornwall have never been seen in Scotland, and vice versa.

Do bare mind when looking at these stats that some of our hubs are very new at the time of publishing this, and haven’t had much search effort yet recorded on iNaturalist. All the data used for this page comes from iNaturalist- check the bottom of the appendices for more information on this.

Hub Name Number of Species Number of Observations
Mount Batten 21 116
Castle Beach 22 289
Menai Bridge 57 757
Ovingdean Beach 3 4
East Sands 3 13
Kilve Beach 0 0
Beadnell Haven 3 12
Lee-on-the-Solent 0 0
Shoeburyness 2 5
The Menai Strait certainly seems to be the place to go for rockpool slug diversity! Huge well done to the volunteers down there that have been finding such an incredible variety of species! But remember, the hub areas used on iNaturalist won’t include observations from snorkelling or diving, and either way I’m sure there are plenty more species to be recorded rockpooling at our newer hubs particularly.

To visualize the different communities, here is an interactive map showing the 1st, 2nd and 3rd most common species recorded currently for each hub. You may have to zoom in on a particular hub to see all of them! Click on each image to get a link to some species information about the slug species, and to see the owner of the image. While some hubs have yet to record any on iNaturalist, I’m sure that will change shortly after publishing this!

Take a look at the appendices below to see the breakdown of each hubs’ slugs!

Menai Straits, Wales:
Photo Common Name Latin Name Number of Observations
Crowned Aeolis Facelina auriculata 74
barnacle-eating dorid Onchidoris bilamellata 63
Pink Coryphella Edmundsella pedata 44
Hairy Spiny Dorid Acanthodoris pilosa 39
Four-lined Polycera Polycera quadrilineata 39
Angular Seaslug Okenia nodosa 37
Sea Lemon Archidoris pseudoargus 36
Sap-sucking Slug Elysia viridis 35
Boston Facelina Facelina bostoniensis 32
NA Aeolidiella glauca 30
citrine nudibranch Pelagella castanea 30
NA Tenellia cuanensis 29
NA Palio nothus 25
NA Aeolidiella alderi 21
Slender Eolis Coryphella gracilis 20
Crimson Hermaea Hermaea bifida 19
Striped Fjordia Coryphella lineata 17
NA Aeolidia filomenae 15
Winged Thecacera Thecacera pennigera 13
Side-gilled Seaslug Berthella plumula 11
NA Coryphella browni 11
Neat Aeolid Cuthonella concinna 10
NA Tenellia foliata 10
crested aeolis Antiopella cristata 10
NA Dendronotus keatleyae 10
Branched Sapsucker Placida dendritica 9
NA Atalodoris pusilla 9
NA Tenellia aurantia 9
Humped Ancula Sea Slug Ancula gibbosa 8
Minute Aeolis Eubranchus exiguus 8
Crowned Seaslug Doto coronata 7
Embleton’s Aeolis Embletonia pulchra 7
Velvet Dorid Jorunna tomentosa 7
Three-coloured Aeolis Eubranchus tricolor 6
NA Doto koenneckeri 6
NA Polycera norvegica 6
Johnston’s balloon eolis Tergipes tergipes 5
Orange-clubbed Sea Slug Limacia clavigera 5
NA Eubranchus farrani 5
NA Doto millbayana 5
Alder’s Seaslug Alderia modesta 4
Flat Limapontia Limapontia depressa 4
Fuzzy Onchidoris Onchidoris muricata 3
NA Janolus hyalinus 2
Salt-and-pepper Nudibranch Caloria elegans 2
NA Rostanga rubra 2
NA Tenellia caerulea 2
NA Capellinia fustifera 2
NA Atalodoris sparsa 2
NA Doris berghi 2
NA Eubranchus viriola 2
NA Capellinia vittata 2
Rim-backed Nudibranch Palio dubia 1
club-gilled nudibranch Eubranchus pallidus 1
NA Geitodoris planata 1
Tuberculate Dorid Adalaria proxima 1
NA Doto hydrallmaniae 1
Castle Beach, Falmouth:
Photo Common Name Latin Name Number of Observations
Spotted Seahare Aplysia punctata 137
Sap-sucking Slug Elysia viridis 44
Side-gilled Seaslug Berthella plumula 35
Crowned Aeolis Facelina auriculata 22
Orange-clubbed Sea Slug Limacia clavigera 22
NA Aeolidia filomenae 20
Velvet Dorid Jorunna tomentosa 11
Gaudy Babakina Babakina anadoni 10
NA Aeolidiella alderi 9
NA Spurilla neapolitana 6
NA Geitodoris planata 5
NA Rostanga rubra 4
White Aeolis Favorinus branchialis 3
Shag-rug Nudibranch Aeolidia papillosa 3
Branched Sapsucker Placida dendritica 2
Four-lined Polycera Polycera quadrilineata 2
NA Facelina annulicornis 2
NA Gargamella rosi 2
Hairy Spiny Dorid Acanthodoris pilosa 1
NA Polycera faeroensis 1
NA Aegires punctilucens 1
NA Trapania maculata 1
Sea Lemon Archidoris pseudoargus 1
Celtic Sea Slug Onchidella celtica 1
crested aeolis Antiopella cristata 1
NA Eubranchus linensis 1
Mount Batten, Plymouth:
Photo Common Name Latin Name Number of Observations
Side-gilled Seaslug Berthella plumula 41
Sea Lemon Archidoris pseudoargus 19
NA Aeolidiella alderi 11
Hairy Spiny Dorid Acanthodoris pilosa 9
Crowned Aeolis Facelina auriculata 8
Orange-clubbed Sea Slug Limacia clavigera 6
NA Aeolidia filomenae 5
Spotted Seahare Aplysia punctata 3
NA Janolus hyalinus 3
Angular Seaslug Okenia nodosa 3
White Aeolis Favorinus branchialis 2
Sap-sucking Slug Elysia viridis 2
NA Palio nothus 2
NA Doris berghi 2
NA Spurilla neapolitana 1
Depilatory Seahare Aplysia depilans 1
NA Geitodoris planata 1
NA Rostanga rubra 1
Shag-rug Nudibranch Aeolidia papillosa 1
NA Polycera norvegica 1
citrine nudibranch Pelagella castanea 1
Ovingdean, Brighton:
Photo Common Name Latin Name Number of Observations
Sap-sucking Slug Elysia viridis 2
NA Aeolidia filomenae 2
Side-gilled Seaslug Berthella plumula 1
Beadnell Haven, Northumberland:
Photo Common Name Latin Name Number of Observations
Side-gilled Seaslug Berthella plumula 6
Sea Lemon Archidoris pseudoargus 6
Spotted Seahare Aplysia punctata 3
Velvet Dorid Jorunna tomentosa 2
East Sands, St Andrews:
Photo Common Name Latin Name Number of Observations
Spotted Seahare Aplysia punctata 8
Sea Lemon Archidoris pseudoargus 4
barnacle-eating dorid Onchidoris bilamellata 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 all our participants record their findings on iNaturalist it also means we can reflect accurately what our contestants have been finding!

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