Thinking about keeping a tarantula, a colony of isopods, or a stick insect and not sure where to start? You’re in the right place — practical answers, honest picks, no fluff, built for people who actually keep these animals.
Invertebrate keeping is one of the fastest-growing corners of the pet world, and for good reason. Many species are quiet, take up very little space, and don’t need daily walks or constant attention. But “low maintenance” doesn’t mean “no maintenance” — invertebrates have precise husbandry needs, and getting the basics wrong is the single biggest reason new keepers lose animals in the first year.
What Counts as a Pet Invertebrate?
The category is broader than most people expect. It includes:
- Tarantulas — by far the most popular pet invertebrate, with hundreds of species varying wildly in temperament and care difficulty.
- Scorpions — hardy, long-lived, and generally easier to keep than people assume.
- Isopods (roly-polies) — increasingly popular as low-effort “cleanup crew” pets and bioactive enclosure additions.
- Millipedes — gentle, slow-moving detritivores that do well in humid bioactive setups.
- Stick and leaf insects — plant-eating, visually striking, and a great entry point for kids under supervision.
- Ant colonies (formicariums) — a niche but growing hobby built around watching colony behavior over time.
- Hermit crabs — technically crustaceans, often grouped with invertebrates, with their own specific humidity and molting needs.
Why People Keep Them
The appeal is real and specific: minimal noise, minimal odor when housed correctly, small footprint, and — for many species — a lifespan measured in years rather than months. Female tarantulas of some species can live 15-20+ years, which is a genuine long-term commitment people don’t always expect going in.
The Four Pillars of Invertebrate Care
Every species is different, but care always comes down to the same four fundamentals — covered in depth in our category guides below.
- Enclosure setup — the right size, substrate depth, and hides for the species’ natural behavior (burrowing vs. arboreal vs. terrestrial).
- Temperature & humidity — the single most common point of failure for new keepers. Most invertebrate deaths trace back to an enclosure that’s too dry, too wet, or swinging between extremes.
- Feeding — appropriately sized prey or plant matter on a schedule that matches the animal’s actual metabolism, not a guess.
- Handling — for many species, the honest answer is “as little as possible.” Handling is for the keeper’s benefit, not the animal’s, and it carries real risk for both of you with some species.
Good Beginner Species
If you’re just starting out, look at animals known for being forgiving of small mistakes: Chilean rose tarantulas and similar hardy terrestrial species, isopod colonies (genuinely hard to get wrong once set up), and stick insects. Skip fast, defensive, or highly venomous species until you’ve got a season of experience under your belt.
Mistakes New Keepers Make
- Misting on a fixed schedule instead of watching the actual substrate and adjusting.
- Buying an enclosure that’s too large for a young or small animal, making food genuinely hard to find.
- Handling a defensive species because it “seems calm” on a given day.
- Skipping quarantine when adding new animals to an existing collection.
Before You Bring One Home
Check your local and state regulations — a handful of invertebrate species are restricted or require permits in some regions. And never release a captive-bred invertebrate outdoors, even a “harmless” one; it’s bad for local ecosystems and, in many places, illegal.
Ready to go deeper? Our guides below cover feeding, health signs, choosing a species, and the gear that actually matters.
Setting Up Your First Enclosure
Enclosure choice depends entirely on how the species actually lives in the wild. Terrestrial species (most tarantulas, scorpions) need more floor space than height, with substrate deep enough to burrow if that’s natural behavior for the species — often 3-6 inches for a burrowing tarantula. Arboreal species (some tarantulas, stick insects) need height over floor space, with vertical climbing surfaces like cork bark or branches. Getting this orientation backwards is one of the most common first-enclosure mistakes: a burrowing species in a tall, mostly-empty tank will often refuse to settle.
Ventilation matters as much as size. Too little airflow and humidity-loving species develop mold or bacterial issues; too much and dry-adapted species can’t hold the humidity they need. Cross-ventilation (openings on two sides, not just the top) generally works better than a single mesh lid for species that need higher humidity.
Understanding Molting
Molting is the process invertebrates use to grow, replacing their exoskeleton periodically throughout life. It’s normal, necessary, and — for new keepers — often mistaken for illness or death. Pre-molt animals typically stop eating, may appear dull or darker in color, and become less active; this can last days to weeks depending on species and age. During and immediately after a molt, the animal is vulnerable — soft-bodied, unable to defend itself well, and at higher risk from handling or disturbance.
The single most important molting rule: never handle an invertebrate that appears to be in pre-molt, and give at least a week of undisturbed recovery time after a molt before resuming any handling or heavy enclosure maintenance.
Feeding Schedules by Life Stage
Feeding frequency changes significantly with age and species. Juveniles of fast-growing species may need feeding every few days; mature adults of slow-metabolism species like larger tarantulas may only need feeding every 1-2 weeks, and some go weeks without eating with no issue at all — especially adult females, which can fast for extended periods without any health concern. Overfeeding is a more common mistake than underfeeding: uneaten live prey left in an enclosure can stress or even injure an invertebrate that isn’t interested in eating, particularly during pre-molt.
Signs of a Healthy vs. Stressed Invertebrate
A healthy invertebrate generally shows steady, deliberate movement, normal feeding response when not in pre-molt, and a full, rounded abdomen (for species like tarantulas, where abdomen size reflects hydration and fat reserves). Warning signs vary by species but commonly include a shriveled or unusually small abdomen, prolonged lethargy with no molt in progress, visible mites or mold on the animal itself, or a curled/contracted leg position at rest for tarantulas specifically, which can indicate dehydration or a more serious health problem.
Sourcing Your Animal Responsibly
Captive-bred animals are almost always the better choice over wild-caught, for the animal’s welfare and often for your success rate too — captive-bred invertebrates tend to be hardier in captivity and don’t place pressure on wild populations. Reputable breeders and specialty invertebrate shops will typically tell you plainly whether an animal is captive-bred or wild-caught (abbreviated CB or WC); if a seller can’t or won’t answer that question, treat it as a red flag.
Bioactive Enclosures Explained
A bioactive enclosure uses a living substrate ecosystem — typically layered drainage material, substrate, leaf litter, live plants, and a cleanup crew of isopods or springtails — to naturally break down waste instead of requiring full manual substrate changes. Done well, it reduces maintenance, holds humidity more stably, and creates a more naturalistic environment. Done poorly (wrong substrate depth, no real drainage layer, or a cleanup crew too small for the enclosure), it can trap excess moisture and cause mold problems worse than a simple setup would.
Bioactive setups work best for keepers who’ve already got the basics down with a simpler enclosure first — it’s a genuine upgrade in complexity, not a beginner default, despite how popular it looks in care videos.
Quarantine Practices for New Arrivals
Any new invertebrate joining an existing collection should spend a quarantine period in a separate enclosure, away from your established animals, typically several weeks. This gives time to spot parasites, mites, or illness before they can spread. It’s an easy step to skip when you’re excited about a new animal, and it’s also the single most preventable cause of losing multiple animals to one introduced problem.
Frequently Asked Questions
No — invertebrates don’t have the brain structures associated with recognizing individual people the way dogs or parrots do. Calmness around a familiar keeper is more likely habituation to routine handling than recognition.
Many species make excellent supervised pets for kids, especially isopods, stick insects, and hardy terrestrial tarantulas — but venomous or defensive species should be adult-handled only.
It varies hugely by species and sex — males of many species live only a few years, while females of some species regularly live 15-20+ years.
Most don’t require UVB the way many reptiles do, though a small number of specialty keepers use low-level UVB for certain species. Check species-specific care sheets rather than assuming either way.
Generally no, unless you’re specifically building a bioactive cleanup crew setup (like isopods with a tarantula) known to coexist safely — most invertebrate species are solitary and will predate on or be stressed by tankmates.
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Frequently Asked Questions
Most commonly kept tarantula species have mild venom comparable to a bee sting at worst, and the bigger practical risk is actually the urticating hairs some New World species flick when stressed, which can irritate skin and eyes. Choosing a calm, well-documented beginner species and minimizing handling reduces the risk to nearly zero.
Most invertebrate keepers never see an exotics vet — there's little a general vet can do for an invertebrate, and most issues are husbandry-related and fixed by adjusting the enclosure. A small number of exotics-specialist vets do exist for serious cases like injury or suspected parasites.
Less than most new keepers assume. Many terrestrial tarantulas do best in an enclosure only slightly larger than their leg span — oversized enclosures can actually make it harder for the animal to find food and feel secure.
Yes, as long as the enclosure is secure and out of reach of curious cats or dogs. The bigger risk usually runs the other way — a startled pet knocking over or damaging the enclosure — so stable, enclosed setups are worth the extra care.
Incorrect humidity is the single most common cause, followed by inappropriate enclosure size and skipping quarantine when introducing new animals. Getting the environment right solves most problems before they start.