So you've seen someone's isopod colony on TikTok, or maybe you held a millipede at a wildlife centre and thought "I could keep one of those." Good news: you probably can. Invertebrate keeping is pretty accessible, and you don't need a spare room or a big budget to get going. But there are a few things worth knowing before you buy anything.
What counts as an exotic invertebrate?
We're talking about animals without backbones that aren't native UK species (or at least aren't your garden woodlice). The hobby covers a wide spread: tropical isopods, flower beetles, jumping spiders, millipedes, mantids, stick insects, cockroaches, and more. Each group has its own care needs, but they share some basics.
One thing to get right from the start: these are different types of animal. Isopods are crustaceans. Spiders are arachnids. Beetles and mantids are insects. Millipedes are diplopods. It matters because their biology is different, and what works for one group can be wrong or even dangerous for another.
Why people keep them
Honestly, for loads of reasons. Some people like the low space requirements. A jumping spider lives happily in a container you could fit on a bookshelf. Others are into the bioactive terrarium side, building little ecosystems with isopods and springtails breaking down leaf litter and waste. Plenty of folks just think they're dead interesting to watch.
The time commitment is lower than most pets. You're not walking an isopod colony or taking a millipede to the vet. That said, "low maintenance" and "no maintenance" are very different things. Neglected colonies crash, enclosures dry out, and animals die quietly if you forget about them.
What you actually need
The basics for most invertebrates are simpler than you'd expect:
- An enclosure (plastic tub, glass terrarium, or acrylic box depending on species)
- Appropriate substrate (this varies hugely by species, and getting it wrong is one of the most common causes of death)
- A way to maintain humidity (spray bottle at minimum, often combined with a moisture-retaining substrate)
- Temperature control if your house drops below 18-20C regularly (heat mats with thermostats are the standard approach)
- Food appropriate to the species
Total startup cost for something like an isopod colony or a stick insect? Often under 30 quid for the enclosure and supplies, plus whatever the animals cost. We'll cover costs properly in a separate post.
The learning curve
There's more to learn than people expect, but less than you might fear. The main thing is understanding that each species has specific requirements for temperature, humidity, substrate, and food. A flower beetle larva eats fermented hardwood flake soil. You can't just shove it in some potting compost and hope for the best. Isopods need calcium for their exoskeletons. Millipede substrate has to be hardwood-based because softwoods like pine and cedar contain phenols that are toxic to them.
The good news is that the keeper community in the UK is active and generous with advice. Forums, Facebook groups, and local invert shows are all good places to learn. People who've been keeping for years are usually happy to help beginners avoid the mistakes they made.
Is it legal?
In the UK, keeping most common exotic invertebrates is perfectly legal. You don't need a Dangerous Wild Animals licence for isopods or flower beetles. Some species are regulated under CITES (certain tarantulas, for example), which means they need paperwork proving they were captive-bred and legally sold. Any decent seller will have this sorted and be upfront about it.
There are no general restrictions on keeping non-native invertebrate species indoors, but releasing exotic species into the wild is illegal under the Wildlife and Countryside Act 1981. Keep your animals contained. If you end up with more than you can house, sell or rehome them within the hobby.
Common worries
People often worry about escapes. Fair enough. A loose jumping spider in your flat isn't ideal, and a colony of tropical cockroaches getting into the walls is a genuine headache. Good husbandry includes secure enclosures with appropriate ventilation that the animals can't squeeze through. Mesh covers, clip-on lids, and ventilation holes smaller than the animal are standard.
Allergies are another question. Millipede defensive secretions can irritate skin and eyes. Some people react to tarantula urticating hairs. Mould and mites in enclosures can trigger respiratory issues in sensitive people. None of this is a reason not to keep inverts, but it's worth being aware of before you commit.
Where to go from here
If you're reading this and thinking "right, I'm in," the next step is figuring out which species suits you. That depends on your space, your budget, how much time you want to spend, and honestly what you find interesting. We've got a guide on choosing your first pet invertebrate that goes through the options properly.
Take your time. Read a few care guides before you buy anything. Talk to other keepers. The animals aren't going anywhere, and a bit of research now saves you from killing something expensive through ignorance later. Nobody enjoys that.