Porcellio Echinatus Isopods

The red edge is not the animal. It is a line somebody selected. The only seller who explains where it comes from says plainly that it was selectively bred for a red band along the outer margin, and the two listings describing the species instead of the morph mention no red at all - one of them describes only silver highlights on the same animal. So Porcellio echinatus is a rough, lumpy grey-brown woodlouse, with the red skirt a thing breeders have concentrated inside it.

Worth saying because the words "red edge" are doing a lot of unearned work in this hobby. At least four unrelated animals are sold under them: this one, a Thai Cubaris that rolls into a ball and is not remotely related, a P. scaber morph, and an unidentified Moroccan Porcellio. If those two words brought you here, check you wanted the spiky European one. Our own Cubaris Red Edge is the other thing entirely.

Where it comes from, corrected

Lucas described it in 1849 from Algeria, and Algeria is still on the map - but only just, at seven records. The species is overwhelmingly Iberian: about 160 Portuguese records across eight districts, 72 Spanish, a few from Gibraltar. Morocco was on this listing until today, and no record of this species from Morocco exists anywhere. That almost certainly leaked in from the unidentified Moroccan animal mentioned above, and it has gone.

This page also called it southern Spanish. The Spanish records reach Navarra and Zaragoza in the north and Toledo and Ciudad Real in the centre, so it is better called an Iberian species with a North African type locality.

Size, honestly

This page said nobody had published an adult size range for this species. That was wrong, and it was wrong because nobody had looked far enough back. Budde-Lund measured a series for his 1885 monograph and gave 12 to 14mm, which is the figure this page now carries and the only published range we can find. It does not sit easily with the other published measurements: Cifuentes figured six males in 2018 running 6.5 to 10mm, which does not overlap Budde-Lund's range at any point. We cannot reconcile the two and will not pretend otherwise - Cifuentes does not say his animals were full-grown, and Budde-Lund does not say what sex his were. Other sellers say 13mm and "up to 2cm"; the 2cm has nothing behind it. Ours are a mid-sized Porcellio, smaller than a hoffmannseggii and bigger than a dwarf.

For what it is worth on availability: a 2024 audit of woodlice sold through Spanish shops recorded this species in fifteen of them at a low price, with four separate commercial varieties against its name. Four varieties is consistent with several selected lines circulating, which is exactly what the red edge appears to be.

Keeping

The texture is the point of this animal - a genuinely rough, tuberculate back that catches the light, which is why one seller sells it as the Shark Skin isopod. Keep it between 18 and 26°C - an unheated room in most British houses - and grade humidity from roughly 50 up to 70%, with one end kept dry.

Five centimetres of substrate, cover made from bark and stone slabs, litter on top, flake soil or rotten hardwood mixed in, calcium always present, protein once a week. Sellers disagree with each other on temperature and humidity by wide margins, which tells you none of them has measured anything, ours included.

No rolling. It runs and it wedges.

Dispatch days are Monday, Tuesday, Wednesday and Thursday. Animals ride in an air-holed pot on damp sphagnum inside doubled card, we add 20% to your count, and the animals are guaranteed alive when the box reaches you.