Finding an Orange Porcellio scaber: Can It Become a New Colour Line?
While looking for isopods in my garden earlier this year, I found one individual among hundreds of ordinary grey rough slaters (Porcellio scaber) that immediately caught my attention. It was a very orange colour, unlike any other Porcellio scaber I had seen in my garden.
Rather than simply admire it and return it to the leaf litter, I decided to begin a small breeding experiment.
There are two common species of isopods living in my garden: Armadillidium vulgare and Porcellio scaber. Colour morphs of Porcellio scaber are well known in captivity, but I was surprised to find such a vivid orange individual living in my own garden.
At this stage I have no idea whether the orange colour is inherited, whether it is controlled by a single gene, several genes, or perhaps not genetic at all. The best way to find out is to allow the colony to breed, and carefully observe the offspring over several generations.
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| Orange slater beside a mottled slater |
There is an important difference between finding an unusual individual and establishing a new colour line. Finding one orange animal doesn't mean I've discovered a new colour line. It only tells me that this particular colour occurs in at least one animal in my local population.
If orange offspring eventually appear, that would give me evidence that the colour has a heritable component. It still wouldn't tell me exactly how the trait is inherited.
This is not a finished experiment with a guaranteed result. It is simply a record of what happened when a rare individual from a wild population was given the chance to reproduce.
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| Orange slater next to mottled slater |
Could orange Porcellio scaber already exist elsewhere?
Yes, they do. Captive breeders have produced and maintained many unusual Porcellio scaber colour forms, including a few orange lines, but finding a striking individual in a completely wild population feels very different.
Establishing the colony
I'm not sure if the orange individual is male or female. It was smaller than most adults, but may have been young as it has since grown to the usual size of adult slaters I see in my garden.
The orange individual was placed into a separate enclosure together with eleven other Porcellio scaber of unknown ages collected from several areas of my garden. I tried to collect adult sized specimens, and tried to get slightly small ones as there is a good chance they are young and have their entire breeding life in front of them.
Among these were several mottled brown and unusually pale individuals because I thought they might add some interesting colour variation to the colony. Three have an unusual grey and orange mottled pattern that I haven't seen commonly among the local population. I don't know whether this represents a recognised colour form or simply natural variation, so for now I'm just treating them as interesting individuals from my garden population. Surprisingly, I also found an albino individual in a different part of my garden, and included it in the mix.
Like my garden colonies, they are kept on leaf litter with pieces of decaying wood, a constant source of calcium from a small piece of cuttlebone, and occasional fresh vegetable matter. Other than providing suitable conditions, I have deliberately tried to interfere as little as possible. My aim is to observe natural breeding rather than force particular pairings.
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| Albino, orange, and grey slaters |
The first generation
After several weeks, the first brood appeared. I was probably far more excited than most people would be. I guess this makes sense, it's probably not realistic to run a long term experiment like this unless you genuinely find it exciting.
Like all young Porcellio scaber, the juveniles are tiny and initially difficult to assess. Their colours continue to develop as they grow, so I couldn't know what colours they would be.
As they matured, however, it became apparent that the great majority resembled ordinary wild Porcellio scaber. Most were grey, while a few showed the same mottled patterns commonly seen in the local population.
The first juveniles have appeared, and most look exactly like ordinary wild Porcellio scaber. I haven't seen a clearly orange juvenile yet. At first this might seem like the experiment has failed. But it is far too early to say that.
One possibility is that the orange colour is controlled by a simple recessive allele. If the orange colour is caused by a recessive mutation, the first generation should appear completely normal even if many individuals carry the gene. This is consistent with breeding observations reported for some orange P. scaber lines, but pigmentation in P. scaber is known to be more complicated than a single gene model, so I don't want to assume that my wild individual follows the same pattern.
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| Several of the colony founders are light in colour |
Why one generation is not enough
One of the interesting things about selective breeding is that unusual colours often disappear before they reappear.
If the orange phenotype were caused by a simple recessive allele, an orange animal bred with a wild coloured animal could produce offspring that all look normal while carrying the orange allele. If the orange allele were recessive, those apparently normal carriers could later produce orange offspring when two carriers bred together.
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| Hopefully plenty of genetic diversity |
Of course, this is only one possibility. Until I observe more generations, I cannot know how the colour is inherited, or even whether it is inherited at all.
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| Mottled orange slater |
Looking more closely at my local population
One unexpected result of this project is that I have started paying much closer attention to the isopods already living in my garden.
Once I began searching carefully, I realised that the local Porcellio scaber population is far more variable than I had first thought. While most individuals are the familiar grey, I regularly find mottled brown animals, almost white individuals, and subtle differences in pattern and texture.
Perhaps the orange individual is simply an exceptionally rare mutation. Or perhaps my local population contains far more hidden genetic diversity than is immediately obvious. Only time will tell.
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| Orange slater newly added to this enclosure |
A longer term project
Like many gardening experiments, this one cannot be rushed. Porcellio scaber takes months to mature, and colour traits may require several generations before clear inheritance patterns emerge. Rather than trying to predict the outcome, I intend to document the colony as it develops.
Whether this eventually produces a stable orange line or simply teaches me more about the natural variation already present in local populations, I think the journey will be just as interesting as the destination. For now, the most interesting question is simple: if I keep breeding these animals, will the orange reappear, and can I stabilise it?
I'll continue documenting the colony as each new generation matures and link future updates from this page.
I sell captive bred slaters through my for sale page. Most are the regular wild colour, although some are mottled or otherwise naturally variable colours.
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