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What is a medically significant animal?

In order to properly regulate the hobby, we need to have some basis of definitions. Unfortunately, there is no clear consensus on what animals are or are not "medically significant". Medically significant is a hobby term, typically when this is discussed in scientific settings they refer to "medically important venomous animals". Usually, this term is reserved for animals that present some threat to human health and safety. Even this isn't clear cut though, for example I couldn't fine a clear cut answer on whether or not honeybees were considered medically important. They do sting people, and that sting could result in a life threatening situation if the person is allergic, but I'm not sure where the consensus is on if a secondary allergy reaction or bacterial infection from the initial sting makes the animal itself medically important. I'm also not sure what amount of risk is required for an animal to be considered medically important. There has been one reported death from a Javanimetrus cyaneus, presumably because someone had a novel severe reaction or some other health complication that reacted poorly with the venom, but in all other sting reports and investigations of this species that risk is extremely unlikely. They are not considered medically important.

The definition I like to use is a "medically significant" animal is an animal where a bite or sting has a reasonable risk of requiring medical attention from a hospital. Bees aren't medically significant, unless you are allergic to them in which case they would be medically significant to you. Javanimetrus cyaneus aren't medically significant because the risk of anything more than mild pain is exceedingly rare.

Venom is also usually placed on a scale in the hobby, to designate the level of risk. This is also up for a lot of debate, so this is the scale I use when talking about scorpions:

1 - Extremely low potency, pain clears up in less than an hour, no lasting effects.

2 - Low potency, pain may last longer than an hour but less than a day, may experience localized swelling or tingling, no lasting effects.

3 - Potent, pain may last longer than a day, systemic effects such as nausea, sweating, light-headedness may occur, a severe reaction may require a hospital visit but usually clears up with no lasting effects. The lowest level of medically significant.

4 - Very potent, systemic effects likely, may require a visit to the hospital, potentially life threatening if there is a severe reaction.

5 - Life threatening, has been known to kill adults, you should immediately go to the hospital.

This can be useful when discussing relative risk when keeping an animal, but all precautions and best practices should be used when dealing with any animal that is medically significant. Remember:

ANYONE can have a bad reaction to ANY VENOM, which could make a sting from ANY species turn into a LIFE THREATENING event!

Risk Mitigation

I often compare keeping medically significant animals to riding a motorcycle. Riding a motorcycle at all is inherently more dangerous than other forms of transport, no matter how safe you are, you are still taking that extra risk. Risk is unavoidable, there is some inherent risk in anything you do. The best thing to do when faced with this reality is to take steps to be as safe and informed as possible about the risks, and to have a plan for what to do if things go wrong.

For riding a motorcycle, this looks like wearing proper protective gear including a helmet, following posted traffic laws, taking a motorcycle riding course and getting a license, and having adequate health insurance to cover you in case of an accident. None of these things will ever completely eliminate the risk of an accident, but being informed and as safe as possible will still help protect you and others.

For medically significant animals, here are some ways to mitigate the risks:

Properly secured enclosure

This is an absolute must. A properly secure enclosure looks different depending on what animal you're talking about. For scorpions, they can't climb smooth surfaces, but are very diligent escape artists and can reach up rather far by balancing on their tails, and access much higher in the enclosure than you would initially think. They are also quite strong, and can open up lids that aren't properly secure. Having a locking mechanism or a double container (a larger container over the smaller one as an extra layer of protection) is also recommended. A secure enclosure can also apply to what's outside and around it. If you have pets, children, guests, or other considerations like that, a properly secure enclosure might also look like a locked room where the container is located, or a locked shelf that is well out of reach. Properly labeling the enclosure to ensure everyone in the house is aware of the potential dangers of the animal is also a good idea.

2. Safe interactions

After the animal has been properly secured, you now have to figure out how to do all the maintenance, feeding, and moving that goes into keeping a pet generally. The most dangerous time of interacting with a medically significant animal is during rehousing, the animal will be stressed from being moved and is likely to be agitated and bolty. If the scorpion has to be moved for rehousing or a related situation (such as placing them together for breeding), proper considerations should be made. I always use double containment, which is basically a larger tub or container that is escape proof that the container the animal is in, and the container it's being moved into both fit inside. One of my closest calls was with my Androctonus bicolor. I was moving him to a larger enclosure, so I had him tailed with a pair of forceps and was lifting him up. He was much stronger than I anticipated, and was able to hook his tail in the forceps and flick himself out of my grip. he landed on the edge of his old container and crawled out, but luckily I had a double container around his old container so instead of ending up on my floor, he ended up safely contained in a larger container. From there I was able to move him to his new container.

Safe interactions also involve awareness of where the scorpion is, and where your hands are at all times. I never let my hands break the plane of the enclosure, they always stay outside. For anything that requires me reaching into the enclosure, I always use forceps. Getting into this habit is imperative, for one if something goes wrong you already have forceps ready and are less likely to instinctively reach out with your hand, for two if you don't know where the scorpion is and you reach for something with your hands, you are much more likely to accidentally squish or spook it and receive a sting.

This should go without saying, but unfortunately there are still too many examples of this and it is the number one reason why people get bit and stung by their pets.

NEVER handle ANY medically significant animal with your bare hands!

There is no reason for it. None of the animals we've discussed for medical significance, including all snakes and arachnids, get any benefit from being handled. There is no benefit to the animal at all. Arachnids are naturally solitary, and being handled is at best just going to annoy them and at worse stress them out. No risk, no matter how small you think it is, is worth bothering your animals for.

I am also including people who intentionally free handle to "prove" how docile the animal is. I don't think this is the proper way to go about education about potentially dangerous species, and I don't think it accomplishes the intended goal. You can explain, for example, that spiders are very reluctant to bite, are skittish, and are not out to attack you. There are many ways to demonstrate a spiders docility, one of my favorite ways is using the "cheese test" from Travis McEnery's "The Spiders in your House" series on Youtube. This can be beneficial to ease people's fear about these animals, without putting yourself in undo danger. I've also demonstrated Brown Recluse reactions to a threat using a paintbrush, or use forceps to demonstrate scorpion defensive behavior.

What isn't safe is holding an animal with your bare hands, intentionally provoking it by pressing it to yourself or harassing it with your finger, or putting it on your face or in your mouth to "prove" that it's safe. For one, it's not safe, it's a medically significant animal and should be treated as such. I also don't think this is modeling safe behaviors with how to interact with these animals, especially when doing education for younger children. Just because an animal is unlikely to bite you, doesn't mean it can't or won't. It just takes them believing they are under threat, which depending on the animal or situation could change. An animal that is generally docile but for whatever reason that day is more on edge, or you pinched it accidentally, or you moved too fast and it got spooked, is liable to bite you. And when bites like this happen, the first thing everyone says is "what did you expect", which only confirms the public perception that these animals are inherently dangerous to be around.

3. Plan for the worst

Even with proper precautions, shit can happen and stuff occasionally goes wrong. It's always better to plan for the possibility there will be an accident than to think it wont happen and be taken by surprise. Have a plan for what you will do in the event of a bite or sting. This can look like having anti-venom on hand, informing your doctor ahead of time of medically significant animals you have in your house so they can give you recommendations, and having a first aid kit and an EpiPen in case of an allergic reaction. Anti-venom can be hard to find, or not available for personal use, and if your local hospital won't carry it for you that's another important thing to factor in when considering the risk of owning these animals.

NEVER think it won't happen to you, complacency leads to ACCIDENTS!

You should also have a plan in case of an escape, keeping your animals in a specific room will help with this, because you can preemptively block small cracks or exits to prevent them from getting into the rest of your house. Have a way to search for and recover the animal if possible, and know what to do in case the animal cannot be recovered. Depending on the animal and how severe the venom is, it may be necessary to call animal control to recover the animal if you cannot find it and it poses a significant danger to yourself or your neighbors.

You should also plan for other disasters. If you live in a place with earthquakes, are your enclosures secure enough to not be knocked off the shelves? If it's a severe earthquake, what will you do if they get knocked over anyway? In the event of a fire, how will you ensure the animal stays contained, and will it be necessary to inform the fire department of it's location? What about with flooding? Obviously it is difficult to imagine dealing with that added stress in the event of a severe disaster, but it is still important to think about.

These three things should be at the forefront of every keepers mind if they are considering keeping medically significant animals. These are general points of consideration, and what the specifics look like heavily depend on what animals you are keeping, but your goal should always be to make keeping as safe as possible for you, your neighbors, and the animal itself.

The Golden Rule

Always show these animals respect. Whenever you're thinking about their care, housing, making a disaster plan, or interacting with them, remember that these animals can potentially kill you. People who don't take the risks seriously or rely too much on their experience get complacent, and that leads to poor husbandry practices and mistakes.

Myths and Misconceptions

"I've been keeping this species for years, I can read it's behavior."

While experience will give you a much better understanding of the animal and will help you anticipate how it will react to different things, that's not a good substitute for proper handling techniques. Every individual is different, and every individual can have days where they're more or less reactive to stimuli. For example, scorpions that are gravid and close to giving birth are considerably more reactive and aggressive than they would be normally. A lot of communal tanks end because one of the scorpions ended up gravid and suddenly killed her tank mates. Animals can also be more easily stressed right before a molt, or if they already are in an agitated state from excess stimuli. Sometimes the animal makes a mistake, if you are hand feeding them they could miss the intended prey item and hit you instead. Experience also doesn't mean you can't make a mistake, and accidentally pinch or scare the animal. This kind of thinking is born of hubris, and it not properly taking into account the actual risks involved.

"This is a docile species."

Similar to the above, just because a species is generally docile doesn't mean they can't or won't bite. Every animal has it's own range of tolerances, or they could be more stressed from other stimuli, or they could mistakenly get you because they missed the intended prey item, or you could pinch them and they believe they are under threat. I don't think every animal needs to be treated like it could go wild at any second and just suddenly attack you, but you should still have a realistic understanding of the risks and realize that even docile species can bite or sting.

"No one should keep these anyway."

A lot of people think the only reason anyone would keep a medically significant animal is because of some masculine driven death wish. We do things that are risky all the time, you're way more likely to get sent to the hospital from a car accident or your neighbor's dog than you are for any of the pets you keep if you practice proper risk mitigation. Venom is not the only draw of these animals, and the goal of keeping them isn't just to prove how much of a badass you are. The hobby tries really hard to self regulate and provide proper education and understanding for animals that have really bad reputations, I personally do a lot of education and outreach on recluse spiders, which are medically significant. Please believe that the people who are showing off their dangerous animals just to get internet attention are a very small minority of us who keep significant animals, and that there are ways to keep them at a reasonable level of safety, and that everyone can make their own decisions on what risks they are or are not willing to accept. I personally will not keep any Ctenidae, because the combination of being medically significant and the ability to climb plastic is not a level of risk I'm willing to accept.

"Doesn't showing a bite provide useful information?"

Potentially it can, but I have a strong dislike of the Youtubers who are taking bites and stings for views. We have bite/sting reports for medically significant species, and you can use multiple testimonies to give a more realistic impression of how the venom would affect you. Everyone reacts differently to pain and venom, so any one bite or demonstration is not that helpful in determining how dangerous an animal actually is. I also think they tend to either over or underexaggerate their reactions, one of the Youtubers I particularly have an issue with is Jack's World of Wildlife. He has taken Loxosceles reclusa bites and continually downplays their significance. He has said he "doesn't consider them to be medically significant at all" even though the video shows he experienced systemic effects. Loxosceles reclusa is also a good example of why these videos don't work for general education, Loxosceles venom is particularly active against fat cells, so bites on the thighs are more severe than bites on the extremities. Jack is a fit, skinny guy taking a bite on his forearm, an area without a lot of fat cells. He is demonstrating what is essentially the best case scenario for a bite (and still experienced systemic effects), how your body will react to a bite will be different. A more reasonable discussion taking into account the range of reported case studies would be more useful for education. I also think these kinds of videos encourage people to try it for themselves to see if it's "really that bad".

Conclusion

General Care

Or, what are we trying to do here anyway?

What is good welfare?

"Animal welfare" is a term that gets used a lot in both animal rights activist circles and animal care circles in general. It generally refers to the well-being of animals in our care, as opposed to the well-being of wild animals. What good animal welfare actually looks like depends on the framework you're using, as well as the animal you're talking about. Invertebrate welfare is not well understood or well studied. A few different texts have tackled the issue in different ways, I personally recommend:

Invertebrate Justice by Russil Durrant (2024)

The Welfare of Invertebrate Animals edited by Claudio Carere and Jennifer Mather (2019)

The Edge of Sentience by Jonathan Birch (2024) Open Access Here

While these books highlight various ethical and welfare considerations that invertebrates face, and discuss some of the different frameworks relating to welfare as applied to invertebrates, there isn't an agreed upon metric for what specifically makes good welfare. It's hard to know what thriving even looks like with regards to invertebrates, and how to best meet the conditions so that the animal thrives and not just survives. I will go over some different frameworks that have been used as a metric to measure animal welfare, and how these may or may not apply to arthropods (and more specifically scorpions).

"As close to natural as possible."

This one is very frequently used in exotic pet keeping circles. The basis of this is that because animals thrive in their native, natural environment, the best way to get them to thrive in captivity is to try to recreate their natural environment as close as possible. Looking at where the animal lives, and how it interacts with it's environment, gives you a great place to start to understand its needs. I do find a lot of limitations in this from a practical standpoint though, although it's a good guiding principle to keep in mind it's not good for determining what you should or shouldn't do to provide quality care for your animals.

For one, it's incredibly vague, and there's a lot of discussion and debate on how close to nature is "good enough". Captivity is already inherently unnatural, and in captivity an animal would not be exposed to the stresses and dangers it would experience in it's native environment. It's generally protected from predators, disease, starvation, and extreme weather conditions, all of which it would experience or have to actively avoid in the wild. There are also things that are natural and within our ability to give that we revoke intentionally because of the risks involved. It is more natural for a snake to eat living prey, for example, but we strongly advocate for feeding frozen/thawed prey instead to protect the snake from injury and disease and because it reduces the suffering of the prey item.

Secondly, the amount of effort and extra attention you put into getting as close to natural as possible is highly variable, and there is a wide range of acceptable ways to do it. The most close to natural way you can keep an animal is in a bioactive enclosure planted with plants from it's native environment, with soil composition that closely matches it's native soil, with a full spectrum and UV/IR lamps to simulate sunlight as closely as possible on a variable time schedule to simulate the natural progression of seasons and the varying in daylight, temperature, and water in regards to those seasons. Although there are people that get fairly close to this, few would argue all of that is necessary and anything less than that is negligence or substandard care. There have been some anecdotal evidence that things like seasonal cooling periods improve breeding in some tarantula genera, for example, but there is no evidence that bioactive enclosures, UVb light exposure, varying day cycles, or drought and monsoon seasons make a measurable difference in tarantula health or behavior.

Five freedoms

The five freedoms is more commonly talked about in animal rights groups. From the Humane Society:

Source

This gives us some more specifics on what makes good welfare. This also breaks up welfare into different domains, with each domain needing to be attended to in order to provide good care. From the example earlier, the reason why we wouldn't feed snakes live prey under this model is to ensure they are free from injury and disease, even though it would be more natural for them. This also specifies stress as a negative aspect in an animal's life. Though stress is something they would encounter in nature, chronic stress leads to decreased fitness and illness; therefore it is good for us to minimize stress.

Where this model gets less specific is when talking about normal behaviors. There isn't a distinction between good behaviors and behaviors that would be undesirable in captivity. Again, using the snake example, eating live prey is the snakes normal behavior, so the risk of the normal behavior and the benefit of performing that behavior would have to be weighed. Breeding is another aspect of concern that isn't mentioned, breeding is a natural behavior but is largely not considered biologically necessary to do, and in many cases it may be more desirable to deny breeding.

Lifespan-focused

This is the simplest model, and the one used most often. With invertebrates, it is often hard for us to objectively measure what good welfare looks like, so all too often people fall back on lifespan. This leads to justifications such as "I kept them like this and they lived ___ number of years" or "I've never had an issue with this, all my animals eat and grow just fine". What these arguments are saying is that the care that the animal is given doesn't negatively impact lifespan, which the keeper is using as the ultimate measure for what good welfare looks like.

This quickly falls apart when viewed from a more holistic stance, hopefully it is well understood that animals can live a long time in subpar conditions. Certain invertebrates and reptiles in particular are very hardy, and can live long lives while still experiencing chronic stress or illness due to inadequate care. Lifespan in invertebrates is also rather easy to influence, in tarantula keeping there is a tactic known as "power feeding" where someone keeps a tarantula on the warmer end of what's comfortable for them and feeds them as often as possible to make them grow more quickly at the cost of their lifespan, inversely you can keep a tarantula cooler and feed less frequently which makes them grow much slower but they will live much longer.

My Metric

"Good welfare is a state created through research based application of native environmental and interpersonal factors that encourages natural behaviors, optimal lifespan, and reduces stress as much as can be practically achieved in captivity."

This isn't meant to be an end all statement on what makes good welfare, but rather what I think is a good guiding principle when deciding what care is appropriate. The phrase "research based application" is meant to highlight which things from nature are important to incorporate, for example the benefits of UVb light in reptiles has been well documented and reported on, so this would be a necessary aspect of their natural environment to provide in your care. Conversely, the benefits of bioactive enclosures in tarantulas is debatable and anecdotal at best, so providing it is not well based in research. Environmental factors include everything from light, heat, humidity, water availability, to prey and food items. Interpersonal factors include conspecifics, the needs of an animal to be around others of it's own kind in a communal set up or it's need to be solitary, as well as interactions with other species such as in symbiotic or mutualistic relationships. The phrase "optimal lifespan" is intended to talk about an animal's lifespan that is not hindered by disease, stress, or poor care, as well as not artificially expanded by techniques such as cooling and minimal feeding. Finally, "as much as can be practically achieved in captivity" is an acknowledgement that captivity is a balance of risk, welfare, and practicality, and that creating a 1 to 1 analog of an animal's natural habitat in your personal care is neither practical nor desirable.

I'm going to focus in more on scorpions, and use the frameworks we talked about above to apply specifically to scorpion care.

Enclosure

There are a few important factors when considering suitable enclosures for scorpions. One of the most important is safety; scorpions are venomous animals, and even the ones that are not medically significant need to be secured properly to avoid escape. Scorpions that are generally considered harmless can still cause allergic reactions, and can potentially harm particularly vulnerable people such as young children and people who are immunocompromised. Small animals and other pets are also likely to react to venom differently than we would, so avoiding escapes is of the utmost importance. Enclosures should be stored somewhere secure where cats and young children can't access, are unlikely to be knocked down, and in an area protected from direct sunlight and drafts. The enclosure itself should have a secure lid; scorpions can be very strong and can push open some types of lids. They can also escape through surprisingly narrow cracks, so all ventilation holes and seams must be small enough to ensure this doesn't happen. Medically significant scorpions should be locked or latched in a way that there is no way for the lid to come loose or be pushed open, and be prominently labeled. It might also be advisable to double contain medically significant scorpions, so their enclosures are kept within larger containers as an extra layer of protection. I talk more about the considerations of keeping medically significant scorpions here.

Both glass and plastic enclosures can be used, though plastic is usually cheaper and provide better ventilation. Glass looks nicer, but usually is only ventilated from the lid and can have a silicone join along the seams that smaller scorpions can easily climb up. Scorpions cannot climb plastic or smooth surfaces, but they can reach up much higher than you would expect because they can use their tail to boost themselves up the side of walls. Pay attention to how tall the enclosure is and how far up the sides ventilation holes are situated.

The size of the enclosure depends on the scorpion. Most scorpions are rather sedentary. Obligate burrowers can stay in their burrows for months at a time. This doesn't mean they don't need any space, rather that for most scorpions usable 3D space is going to be more important than the exact dimensions of the enclosure. Fossorial scorpions should have enough vertical substrate space that they can make a burrow that completely encases them. Substrate depth about the same length as the scorpion is stretched out is typical. Arboreal scorpions need about the same amount of space vertically, plus a bit extra so they have enough room to molt properly. Using hides, hills, and enclosure decor can create more usable space in a smaller enclosure, sloping the substrate in a hill, for example, allows for a deep burrow while also providing more open air space than if you leveled off the substrate evenly throughout the enclosure.

As a basic thumb rule, the scorpion should be allowed to move around comfortably, be able to fully lift it's tail in the air and threat pose without touching the roof of the enclosure, have enough walkable space to be able to extend it's tail out and defecate, and have enough space to molt in. If your scorpion can touch opposite sides of the enclosure with its claws and tail stretched out, it's probably too small. Communal set ups should have enough room for each scorpion to be able to do each of these things comfortably without crossing into their fellow scorpions space, plus extra as a safety margin. Enclosures should not be so large that finding prey is difficult or the scorpion would get lost.

Slings are often kept in smaller, more basic enclosures for convenience and ease of maintenance. This is about as small as is acceptable an enclosure, this scorpion would need to be upgraded again before their next molt.

Hides

Hides and vertical surfaces are easy to provide. There are a lot of different materials you can use to provide a suitable hide. Generally, the hide should be large enough that it fully covers the scorpion, or if it's a vertical surface that it's big enough that the scorpion can hang underneath it and be entirely covered. Hadrurus scorpions in particular really like to dig, if they don't have borrowable substrate providing a hide that is large enough that they can dig a chamber underneath without it collapsing, shifting, or without substrate falling down and letting light in is necessary. Otherwise they will keep digging and moving around the hide. Vertical surfaces need to have some clear space underneath to allow arboreal scorpions to molt, typically a bit more space than the scorpion is long.

Cork bark is a good go-to material for hides, it's lightweight, easy to break into pieces to get the right size, resistant to mold, and provides a good gripping surface. It can be laid flat on the ground or angled for a vertical hide. Finding more curved pieces and shoving them into the substrate at a steep angle, or by sloping the substrate on one end of the enclosure and inserting the cork bark into the "hill" will give a great starter burrow that really encourages burrowing. I've also been using pieces of terra cotta pot as a hide in desert enclosures, because when moistened the fact that it's porous allows an increase in humidity under the piece without wetting the substrate. It also is more heavily curved than cork bark, so provides more space underneath it.

Care needs to be taken when using hard, rough materials like terra cotta or rocks, I had been finding weird discoloration on my Leiurus quinquestriatus and I had no idea what was causing it. I asked a scorpionologist about it, and she suggested the top of the scorpion might have been rubbing against something, causing wear and discoloration on the cuticle.

Discoloration and wear on the "high points" on top of the scorpion through multiple molts.

From this, I came to the realization that when given a rough hide and shallower substrate, the scorpion had to squeeze under the hide, which caused her cuticle to rub against the lip and edges of the terra cotta. Deeper substrate remedied this issue, as she was able to dig more underneath the hide, and in her most recent molt these marks got considerably better. This is something you should be aware of if you're using terra cotta or rocks as hide materials.

Most recent LQ molt.

For arboreal scorpions, people have also had great success using strips of cork board because it's light, mold resistant, and can easily be cut to fit the enclosure. Amblypygi keepers typically use this or Styrofoam, which although Styrofoam would work for scorpions as well this doesn't seem to be very common.

Regardless of what specific material you choose, some sort of hide or retreat is absolutely necessary. Scorpions tend to like smaller, tighter spaces, and will avoid light when possible. Not providing a safe retreat will cause chronic stress, which is bad for your scorpion's health. I am personally of the opinion that borrowing species do not need to strictly have a burrow into the substrate if a suitable hide is provided, but there are other keepers who disagree with this statement. Some keepers only provide a burrow and do not provide any extra structure of a hide whatsoever, which definitely also meets the needs of the scorpion. However you chose to go about it, the scorpions behavior and habits should be monitored for signs of stress. Even with a hide, a scorpion may not like using it for whatever reason and still exhibit stress behaviors. These behaviors are important to recognize so that you can troubleshoot your enclosure and ensure the scorpion is feeling comfortable. I have a post about recognizing scorpion behavior here.

Substrate

Substrate selection is very important, as substrate is crucial to maintaining proper humidity and allowing for the formation of burrows. I have my own personal opinions on which substrates I prefer, but there are a lot of substrates that work well for scorpions. First I will briefly talk about substrates that should not be used.

Wood chips, Reptibark, Aspen shavings, ect

Any sort of wood that comes in pieces or has sharp edges is not good for scorpions. For one, they're not very great at holding moisture, they tend to get moldy really quickly when kept consistently wet. Sharp edges and pieces can also injure a scorpion, especially during molting. These should be avoided all together.

Calcium sand

Calcium sand is just calcium carbonate in powdered form, and is dangerous to use with any animal. It's dusty, and can potentially cause irritation to the respiratory system. It also dissolves in water, so if it ever gets wet the sand will become a paste then harden into a rock-like shell. This can get stuck on your scorpions tarsi, or more dangerously on your scorpion's tail while defecating, causing impaction, or on their spiracles.

Vermiculite

Vermiculite is a kind of potting soil additive that increases drainage in pots. This was an extremely popular substrate early in the hobby because it was cheap, readily available, and didn't mold. A lot of older care guides recommend vermiculite. It's alright as an additive to aerate the substrate, but used by itself it's dusty, hard to burrow in, and is an uncomfortable consistency because it's so chunky.

Gravel

Similar to vermiculite, gravel is an uncomfortable consistency and can't be burrowed into. Gravel is also heavy and doesn't retain moisture. It can be used as an additive but I would limit it to smaller amounts.

Paper towels

Paper towels can be used in quarantine enclosures or in temporary enclosures to monitor a sick scorpion, but should not be used as substrate. They can't be burrowed into and are inconsistent with maintaining moisture, and mold.

Now I will talk about substrates that can be used. The exact mixtures and ratios of these will depend on the kind of scorpion you have, and I will talk about my personal opinions about these substrates and what I prefer to use in my enclosures, but all of the following substrates are safe and suitable for scorpions.

Topsoil

One of the best substrates overall, can be used by itself to cater to more temperate and tropical animals or mixed with other substrates for savannah and desert scorpions. Usually made of a mixture of a few different things, the exact mix is not very important but you must ensure the soil does not have any added fertilizers or pesticides. Organic topsoil is usually safe for invertebrates, but you should also check the ingredient list. Topsoil is the preferred choice if you are going to make a bioactive enclosure.

Peat Moss

Similar properties to topsoil but can be cheaper or easier to get in smaller quantities. Readily retains moisture and burrows, can be used by itself or as an additive.

Coco coir

A substrate made by mulching coconut husk, this one is very commonly used in the hobby because it is extremely cheap and easy to buy in bulk. It typically comes in a compressed brick that can be hydrated and broken up into soil. Personally, I would only use it as an additive to help aerate the substrate, I'm not fond of it used by itself. From personal experience, I find it dries out very quickly and gets dusty, and in it's dry state it does not support a burrow very well. If you do keep it wet though, it molds very easily. The mold can be managed with springtails, and this is one of the more common substrates used, so it definitely works fine and people have had great success with it. I just find peat moss or top soil to be a lot better for moisture retention and burrowing.

Clay

Clay can be a valuable additive to arid substrates to help support burrowing. I would also use caution with it and not use it as the bulk majority of a substrate. Clay, like calcium sand, has the tendency to become mud when wet then cake onto tarsi or tails. With desert scorpions, this is almost a guarantee to cause mycosis. In smaller percentages this problem is not very common, I would keep the amount of clay under 30% of the total bulk.

Play Sand

The go-to for arid and desert set ups, play sand can be used by itself for scorpions that are adapted to dunes or with an additive to support burrowing. My preferred mixture is play sand with peat moss mixed in to the amount I want based on the scorpions natural habitat, with more or less peat moss to control moisture retention. People also have great success mixing play sand and clay, or you could mix all three together to get different consistencies and effects.

Water

This section will be about drinking water. Water is extremely important for scorpions, I believe it is one of the most neglected aspects of scorpion care and causes most of the "random" deaths in the hobby. There is a common adage that scorpions get all their water from their food, and so water is often not provided at all. Though in the wild scorpions can get all their water requirements from their food, they still will drink water when available, and especially in desert environments it is often overlooked the amount of water they do have access too. Deserts still experience dew and frost in the early mornings when scorpions are active, and several species (in particular Centruroides sculpturatus) are known to seek out humid microclimates and sources of water [Source].

The main reason people tend to be cautious about providing water is that water is difficult to balance, as scorpions are prone to drowning and many desert scorpions do poorly in constant moisture. There is a general sentiment that providing water will cause mycosis in desert scorpions, or that the risk of drowning is too high for it to be worth it. Drinking water alone does not cause mycosis, constantly wet substrate and stagnant conditions cause mycosis, and there are different ways you can provide water to limit the risk of drowning.

Water can be provided in one of two ways. Either a water dish can be filled for the scorpion or you can mist the sides of the enclosure and allow the scorpion to drink the droplets off the side. There has been conflicting statements on whether or not scorpions can absorb water from the substrate directly, the paper that directly tested if Hadrurus arizonensis can absorb water from a wet sponge determined that "Although many individuals demonstrated a limited ability to absorb water from moist substrates, the amounts were well below levels necessary to be important as a method for replenishing supplies of body water. It was concluded that water uptake from a subsaturated atmosphere or a moist substrate plays little or no role in the water economy of H. arizonensis, regardless of its hydration state." [Source] Baby scorpions can drink small water droplets out of moist substrate and moss, but for the most part scorpions need water in some sort of free form to be able to drink it.

For most tropical scorpions, a water dish can be provided at all times. The water dish should be small enough that the scorpion can easily lift itself out of the water. Exceptions are for large scorpions in the Heterometrus genus, these scorpions are very accustomed to water and are large enough that a deep water dish is generally safe, provided there is some way for them to climb out. In the wild, they'll readily enter pools and puddles. A large water dish can be an important source of enrichment for them.

This scorpion is soaking, the rocks ensure she can easily climb out and won't get trapped by the smooth sides of the water bowl. She was in the water bowl often, even catching prey on land and choosing to eat it in the water.

Scorpions aren't naturally hydrophobic like most spiders are, and at certain sizes water tension will be enough to trap them and cause them to drown. I've even seen baby scorpions drown on condensation on the side of an enclosure. For small scorpions, keeping the substrate slightly moist with a dropper and providing an extremely light misting is adequate for their water needs. I use a hair salon mister because it provides a very light even spray, this allows for tiny droplets that closely mimic dew. The droplets also evaporate quickly, so for arid scorpions that won't tolerate wet substrate it's the best way to ensure they are drinking. Scorpions also seem to have limited ability to drink from water dishes that are too small, the ideal size seems to be one they can comfortably fit the width of their prosoma into.

Drinking from a small dish, a larger dish, and pooled condensation on the substrate.

Desert scorpions are prone to mycosis and will not tolerate constantly wet conditions. Water dishes do not need to be provided constantly to be beneficial. For desert scorpions, a water dish provided monthly is all that is required. Younger scorpions are more prone to desiccation than adults are and need more access to water than they would as an adult, but are also usually small enough that misting the sides as above works well for them.

Water should not be provided through paper towels, a sponge, or water crystals. There is limited evidence scorpions can take up water through moistened sponges or paper towels, and these two can harbor bacteria. Scorpions are unable to drink water from water crystals or gels at all, and are useless in providing drinking water.

Food

The nutritional requirements of arachnids is very poorly understood. I will be giving my thoughts on scorpion feeding and nutrition, but please understand that there are very few tested practices with feeding so this is based on my own experience and anecdotes I've read from other keepers.

Scorpions eat other invertebrates, the most common feeders being crickets, roaches, and mealworms. Flies can also be used, fruit flies especially are readily taken by small arboreal scorpions, but for the most part anything that is going to be able to climb to the lid of the enclosure will be able to avoid capture for a very long time. Large scorpions can also take large feeders such as hornworms. Vertebrates are generally discouraged from being used as feeders. Though large scorpions can eat frozen/thawed mice, it's generally messy, and not biologically necessary for them.

My favorite feeders to use are crickets; they are easily bred in captivity, very active and draw an excellent prey response, do not burrow, do not climb plastic, and are relatively soft. Their generalist diets makes them extremely easy to gutload, and they grow very quickly and reproduce very fast. They also come in a variety of sizes, with pinheads being perfect for tiny slings and the adults being large enough to suit the larger scorpions. I also find them to be a bit fattier, moister, and more filling than similarly sized roaches. They also tend to be lower in chitin and ash than other feeders like mealworms or dubia, which could make them more digestible.

Red runner roaches are also an excellent choice for scorpions. They also are very active and give a great prey response, and don't burrow or climb. They are also quieter than crickets which most people see as a boon. I find their care requirements to be a bit harder to meet for me personally as they need it a bit hotter and need moist substrate, which needs to be changed out to prevent the buildup of frass. Their frass is also known to cause allergic reactions through repeated exposure, so need more care taken when handling them or doing tank maintenance. Overall though, these are an extremely good pick for feeders.

Mealworms and superworms are great for specific scenarios, but not my preferred option for general feeders. They work best when cut up to allow for smaller scorpions to scavenge off the pieces because their harder shell prevents the piece from drying out before the scorpion can get to it. Large superworms are also great for larger scorpions, though I would always give them to the scorpion directly instead of letting the scorpion hunt for it by itself. I wouldn't let a mealworm or superworm free in an enclosure unsupervised because they will almost always immediately burrow under the substrate. This is an issue both because you then can't tell if the scorpion actually ate or not, and because they can be extremely dangerous to the scorpion if allowed to live in the enclosure. A molting scorpion is an easy target. I've even heard of mealworms having their heads partially crushed and still being found as beetles in the enclosure months later. I also think they tend to be harder and not have as much substance to them for their size. Still a feeder I end up using fairly often, but not my go to.

Waxworms are fairly small, so larger scorpions are often not interested in them. They also tend to be fatty, and so are discouraged from being used too often in reptile communities. I also find they don't get a great feeding response usually, but when given directly to a scorpion they are very soft and easy to eat and can be very useful for bulking up a skinny scorpion.

Dubia roaches are also commonly used, but I personally don't think they're a great choice for scorpions. They're very flat, which can be hard to grab, and they tend to freeze when bothered. Scorpions often have trouble finding them and grabbing them accurately, and even once grabbed can have trouble finding a place to sting. If your scorpion will take prey directly from forceps though they're a fine choice. They don't burrow very well, don't climb smooth surfaces, and are easy to rear in captivity. They're very frequently used in tarantula keeping, spiders seem to have an easier time with them.

No matter which feeders you use, it's generally better to breed them yourself than getting them from a pet store. Breeding yourself can ensure that the feeders are kept in the best possible conditions, and are fed an appropriate varied diet that allows them to be the most nutritious possible for your scorpions. You can also more closely monitor for disease and infection, and cull any animals that might be a potential health hazard to your other animals.

While I don't think buying feeders from pet stores is bad, I've become a lot more skeptical about the food that is given to them during the farming process and the quality of their care both before and in the pet store. Whether you're using synesthetic or whole food diet, I think you should be aware of what your feeders have been eating, and at least keep them under observation for a while to gutload them properly and monitor them for disease. Healthy feeders make for better quality food for your scorpions.

I've also seen people suggest to rotate feeders for variety. I don't think there's strong support that variety is necessary; people have raised scorpions on a single species of feeder for years, and I would also point out that when people say to "rotate feeders" they're typically talking about rotating between two or three commonly available species. I don't think that would make much of a difference, especially if you're giving all your feeders the same diet and thus giving them all access to the same nutrients or deficits in nutrients that the diet has. I would agree with this more on principle if people were using a variety of diets and rotating between multiple different orders of bug to more closely match with what the scorpions would be eating in the wild, for example including animals that are not typically used as feeders such as spiders, other scorpions, centipedes, and worms.

Temperature

Along with water, temperature is the most important thing to consider when keeping scorpions in captivity. Scorpions largely live in warm environments, with only a few notable species being adapted to areas that stay relatively cool for long periods of time. They are poikilotherms, which means their internal body temperature fluctuates with environmental temperature.

Adequately warm temperatures are vital to a scorpions growth and development, scorpions that are kept too cold will grow extremely slowly, eat much less, and become sluggish and inactive. In the wild, scorpions are more surface active on warmer nights than colder nights [Source 1, 2, 3]. Scorpions that are kept excessively cold will die. Warm temperatures also play an important role in digestion, and has been shown to improve immune response in other arthropods [Source 1, 2], so this may be the case in scorpions also. Scorpions in captivity will frequently seek out warm areas to bask under. One study on Centruroides sculpturatus also suggests that gravid scorpions will seek warmer than normal temperatures during development, which may help with reproductive success [Source].

The scorpions ideal temperature can be guessed at using the temperature range in it's native habitat, but there some caveats with this approach.

For example, this is the yearly air temperature in Guadalupe, Arizona.

Source

Source

This study done on Hadrurus arizonensis measured the burrow temperatures of three scorpions in Guadelupe, Arizona over the course of 3 days in June. Though the air temperatures indicate a fairly large fluctuation (between 78-103F), soil surface readings were much higher than that due to direct absorption of radiation from the sun, and burrow readings were a lot more stable. Extremely high temperatures from the soil surface gradually warm up the burrow because it takes time for the heat of the soil surface to be transferred deeper into the soil via conduction, so the peak temperature in the burrow occurs after the peak temperature at the surface. When night falls, the surface rapidly cools through heat loss to the atmosphere, but the "slug" of heat energy deeper in the soil can only be dissipated by either being transferred deeper into the soil or being transferred back up to the surface. By the time temperatures have started to cool, the sun has risen and the soil heats up again. This makes for a very stable temperature in the burrow, though conditions vary depending on season, moisture, and type of substrate. Generally, burrow temperatures will be consistently slightly warmer than the lowest air temperature in the area and slightly cooler than the hottest air temperature.

Source

Another graph that demonstrates heat flux through the soil.

This is just to point out that temperatures cannot be copied directly from the air temperature readings of the scorpion's native habitat. Aside from burrows, the scorpions actively thermoregulating by seeking shade or cooler microclimates, or inversely seeking warm microclimates and protection from frost and cold by burrowing deep into logs or leaf litter means it's hard to know for sure exactly what temperatures the animal is experiencing throughout the course of a year. Desert climates are also more difficult to judge accurately than tropical climates, I wish the study I posted earlier had data for what temperature the scorpions experienced during the winter, where air temperatures drop dramatically. Desert scorpions also experience more fluctuation from day to night.

Generally, providing a temperature gradient is helpful because it allows the scorpion to regulate it's own temperature. Some keepers may provide a higher daytime temperature and cool down the enclosure at night, others don't provide a gradient at all but keep the enclosure relatively warm constantly. Personally, I tend to keep all my scorpions at around 80F (with some exceptions) and cool down a bit during winter to around 75F. I firmly believe no scorpion thrives being kept constantly under 70F, and above a 75F hot spot or daytime temp is required. If you are cooling down the enclosure or providing a gradient, a higher hot temperature can be used.

The exceptions come with desert scorpions from the MENA (Middle East and North Africa) region, in particular those that do not burrow. Leiurus and Androctonus are scrapers, meaning they do not dig deep into the substrate to escape the heat. Daytime temps in the summers of this region are also extreme, frequently reaching over 110F. These scorpions, and scorpions that are behaviorally similar, do not thrive in colder temperatures. I recommend a hot spot or a daytime temperature over 90F, I provide mine with a hot spot of 95F and a cooler spot of 80F, some breeders that specialize in these scorpions recommend hotspots of 100F.

For desert burrowers like Hadrurus, temperature can be tricky. While they are certainly tolerant to cold periods, it's unclear if cooling improves their health or welfare or is just a hardship they are adapted to endure. There is also debate on whether night time cool periods or seasonal cool periods are more beneficial, or if neither or both are needed. Whether or not you as a keeper decided to do nightly cool periods, seasonal cool periods, a temperature gradient, or multiple/none of these is dependent on what is practical for you and what anecdotal evidence you find persuasive and important to incorporate. Seasonal cool periods have been suggested to improve mating success in certain genera of tarantula, namely Grammostola. From personal experience, I have not seen any benefit to cool periods in scorpions but I do provide gradients for the scorpions that have a hotter heat spot and I do a slight seasonal cooling period.

What is not acceptable is seeing that desert scorpions can be tolerant to colder conditions and keeping them at room temperatures year round. Room temperatures are often significantly cooler than they would experience in the wild, and the mantra of "if you're comfortable, they're comfortable" encourages keepers to not measure the temperature of their enclosure and not regulate it whatsoever. Room temperature also changes from person to person, I do know people who keep their houses below 65F year round. Heat is necessary for them to thrive, they need to have access to an appreciable amount of heat at least seasonally. An important disclaimer to this, especially when comparing care advice given by other people, is the strict bounds of acceptable temperature are not well understood. People have kept scorpions relatively cold and not had issues, and we don't know what temperatures are too low for them to thrive and what temperatures are accepted but not preferred. This can make it difficult to draw conclusions about which native temperature ranges are biologically important to incorporate into captive care.

Tropical scorpions such as Heterometrus have native conditions that suggest they do not tolerate constant room temperatures. In their native habitats, air temperatures rarely get below 70F and even in the winter day temps are frequently above 80F. Tropical climates experience a much steadier constant heat than desert climates and extreme cooling is not common. Because Heterometrus silenus are so commonly kept, most of the issues I see with temperature involve this species. Though they do fast habitually, a vast majority of the time when a new keeper complains about their scorpion refusing food it is because they are kept too cold. For these species I recommend around 80F consistently, with only a minor nightly or seasonal temperature drop if any.

Table comparing the temperatures of the air vs within a burrow for the tropical scorpion Heterometrus fulvipes in January. Even during nightly temperature drops in winter, the burrow temperature stays relatively warm and consistent. Source

Heat can generally be provided through heat pads or heat lamps, or through simply temperature controlling the whole space where your enclosures are stored. Heat pads should always be placed on the sides of the enclosures, scorpions will burrow to try to escape the heat which can lead to them overheating if the heat source is coming from the bottom of the tank. CHE are my preferred method of heating that provides a heat gradient, they do not emit any light and are very reliable. Other kinds of red light heat lamps can be used, halogens and other such heat lamps are usually too strong for what is required in a scorpion enclosure and strong lights should be discouraged. Scorpions are photophobic and avoid light when possible. Additionally, any sort of UV or black light should not be used, especially at night when used for the purpose of showing off a scorpion's florescence. Not only does this disturb their circadian rhythm and nighttime activity, but excessive exposure can strip away the florescence compounds in the scorpions cuticle.

For heating the whole space, various office and home ceramic heaters or radiators work perfectly, I have found there are several you can connect to an external thermostat as well if it doesn't have built in temperature control. The one I use is set on a thermostat that goes to a probe in front of my scorpion shelf, so it kicks on when the shelf gets to 78F and kicks off at 82F. I have seen people use indoor grow tents or similar structures for more insulation and more precise temperature control.

No matter which heating element you use, a thermostat is absolutely required. This allows heating elements to be controlled so they do not overheat your enclosures, and allows you to know how warm your enclosures are. Even if you determine that your house is warm enough for you to not need extra heating elements, still make sure you either have an accurate thermometer or a temperature gun so you can measure the temperature of the enclosure. There are many microclimates in your house even with central heating and cooling and even though your house thermostat may say 76F, the enclosure may experience fluctuations way beyond that. I prefer to have a thermometer that gives the max and min temperature range observed, temperature guns are good to measure at precise spots but wont tell you the range experienced in an enclosure.

Humidity and Ventilation

Humidity is a complicated factor that is a product of both ventilation, temperature, and water. Higher ventilation will reduce the humidity in an enclosure because evaporated water will be wicked out of the enclosure more quickly (your house is generally fairly dry). Higher temperatures hold more moisture, meaning more water can be suspended in the air. This does not always mean there is a higher relative humidity (RH). RH is usually expressed as a percentage, and is representative of the amount of saturation of the air at a given temperature. Let's say air at 80F can hold 100ml of water vapor in it before it reaches saturation and starts to precipitate or condense. The air currently has 40ml of water vapor in it, meaning it is at 40% RH. When cooled down to 40F, the air can now only hold 50ml of water vapor in it. With the same amount of water vapor as before, 40ml, RH is now 80%. This is an extremely basic demonstration to explain a point, vapor curves are fairly complicated and there are different curves depending on temperature and other factors, but this is why condensation forms in your enclosures when the temperature drops. Not because more water vapor was added into the air, but because the temperature dropped to where the water vapor that was already in the air is at saturation and precipitated out as condensation.

The usefulness of measuring this percentage exactly is debatable. While higher saturations reduce water loss through respiration, temperature is generally a greater factor in both the metabolic (therefore respiratory) rate of scorpions and in the amount of water lost through both respiration and through the cuticle [Source]. Similarly, while the ability for scorpions to drink or absorb moisture out of saturated substrates is debatable, there is no evidence they can absorb moisture from the air or that sufficiently saturated air will prevent them from dehydrating.

Humidity and ventilation are more important in terms of disease prevention. Even for tropical scorpions, enclosures should have enough airflow that conditions don't become too stagnant. High humidity and stagnant air is linked to various fungal diseases, especially in desert scorpions. It is important to note however than in a few studies that have measured the humidity of desert burrowing scorpions, RH seems to be much higher than assumed. Hadrurus burrows were measured at a RH of 55-70% and Pauroctonus utahensis were suggested to be over 95% [Source 1,2]. More information is needed to draw conclusions about this, but from anecdotal evidence high humidity and stagnant conditions should still be avoided. Molting issues can also be caused by low humidity, in low humidity the outer cuticle dries and becomes stiff before the scorpion is able to free itself.

Community

In this section I will be talking about both scorpions being kept with other scorpions and scorpions being kept with other animals.

First keeping scorpions communally. Scorpions are not social animals, they do not have any requirement to be housed together and largely gain no benefit from it. Cannibalism is also always a risk in these set ups, scorpions are frequently cannibalistic and in some areas the main predator of scorpions is other scorpions. There is no way to house scorpions together where cannibalism is not a risk.

That being said, the risk of cannibalism is dependent on a lot of different factors, and in the wild there are instances where scorpions do live together. The clearest cases for communal living are in scorpions that are parthenogenetic and so tend to live in large "colonies" in the wild. Tityus stigmurus and Tityus serrulatus have a well documented track record of living together, and cannibalism is not common if the scorpions are well fed and have a lot of space. Other bark scorpions such as non-parthenogenetic Tityus and Centruroides also tend to live in groups, in the wild they will colonize a tree or a suitable log and so will be in close proximity to each other. The scorpions need to be kept well fed and provided with enough hides that they can avoid each other, but generally cannibalism is rare. The exception is with gravid females, gravid females frequently get more aggressive the closer they are to giving birth and most cannibalism instances in these kinds of set ups happen because the keeper was not paying attention and did not realize one of their females was close to giving birth. Gravid females should also be separated to protect her brood, as other scorpions will opportunistically eat them while they are on their mother's back.

The other instance of communal living that is supported by wild behavior is the maternal care that some scorpions provide to early instars. Especially in Heterometrus species, babies will often stay with their mother and live together in their mother's burrow until 3 or 4i. The mother allows her brood to scavenge off her kills and the young have even been observed working together to take down larger prey [Source]. Some keepers assert that raising the babies with their mom results in larger, healthier scorpions. Smaller, weaker individuals from the brood are also generally eaten, which helps ensure only the scorpions that would've survived anyway get fed and cared for.

Some people will keep unrelated adults together communally. This is especially common with Pandinus and Heterometrus species, which are generally considered to be more docile. The reasoning essentially says that if you give them plenty of space, hides, and food, there is no reason for them to attack each other. I find this flawed for several reasons. For one, scorpions don't only attack each other out of a drive for food, as mentioned earlier gravid females will also frequently become aggressive with each other, and they can become territorial to other scorpions even without being hungry or out of maternal instinct. Two, if there is a large size discrepancy, such as if you are keeping immatures with the mother and an unrelated adult is also in the enclosure with them, or if there is just one scorpion that's a lot larger than the other, cannibalism can still occur even if both scorpions are fed well because the smaller scorpion may just be seen as too good of a meal to pass up. Scorpions can eat a lot and how full they are can change depending on other factors. A scorpion that is fasting for example might refuse all food regardless of body condition, while a scorpion that has decided to gorge will eat whatever is available almost without end, and it can be hard to anticipate those changes in a communal set up. Three the assumption is usually that if provided enough space and hides the scorpions won't ever leave their burrows and so will never encounter each other, which is not the case. Though scorpions tend to be relatively sedentary, they do still explore and it's unrealistic to assume they will never interact with each other. The larger point against this is there is absolutely no reason for it. Scorpions do not do better living with conspecifics, and if they are frequently fighting over territory or trying to avoid each other to avoid predation they are going to experience constant stress. It gives them no benefit and in many ways can make their lives worse, and puts them at risk for cannibalism. There's no reason for it.

Now I'm going to talk about scorpions living with other organisms, both as CUC and as bioactive set ups. Clean up crew is a catch all that refers to other smaller animals that are included into the tank for the purpose of controlling mold and cleaning up waste and left over food. Typically these will be either springtails or isopods, and it's more common to have them in a moist enclosure than an arid one. Springtails can be very helpful, leftover food and waste scraps mold, and can attract mites or phorid flies, neither of which are desirable. Springtails help by both directly eating the leftovers and outcompeting these other animals because they breed extremely quickly. I also like including springtails in extremely tiny scorpion's enclosure as supplemental food if I am unable to feed them as frequently as they need.

Isopods accomplish this same task, but are generally not recommended. For one, isopods tend to not just eat mold, and would prefer almost anything else, which makes them less effective at mold control. They can also breed very quickly, especially the species that are typically used as a CUC. Dwarf white isopods can quickly overwhelm your tank and stress out your scorpion with pure numbers, and they're parthenogenetic and extremely hard to control once they've established. They can also be rather aggressive, Porcellio especially are rather bold and will attack other animals in the tank, this combined with large numbers can result in a dead scorpion. Even with gentler species, molting is a risky time and most isopods will opportunistically nibble at a vulnerable scorpion. They are also larger than springtails, and can cause extra stress by constantly running over and interacting with your scorpion.

In Hadrurus enclosures, Asbolus verrucosus are sometimes used as CUC and tankmates. This is based on observations of the beetles sharing burrows with the scorpions in the wild. The scorpions are unable to kill the beetles because they are so heavily armored, and the beetles generally leave the scorpion alone. Although there is minimal harm in this arrangement, it is largely unnecessary. Scorpions produce very little waste, and in an arid set up mold is not typically an issue. Scorpions will push uneaten food out of their burrows, so there is no need to employ a clean up crew to eat waste. Being rather large, the beetle can also cause the scorpion stress by continually interacting with or walking over it. I also think the justification for this is pretty slim, though the beetles may occasionally be found in scorpion burrows there is no evidence they form any sort of ongoing symbiotic relationship (such as those formed between frogs and certain types of tarantula species) or long term relationship at all.

CUC are sometimes used in conjunction with bioactive enclosures, which are enclosures that include plants, a microbiome, and other biotic factors to mimic the nutrient cycling of a full ecosystem. Aside from aesthetic appeal, bioactive enclosures have not been shown to be beneficial for the scorpions wellbeing in anyway. Scorpions produce very little waste, so they do not need a large team of CUC and active soil bacteria to maintain cleanliness of the tank, and other factors that are used to maintain the bioactive enclosure may be detrimental. Scorpions are photophobic and will not appreciate having bright grow lights on for a significant period of time to grow plants, and excessive watering of the substrate for plant life can make the substrate too moist. Burrowing scorpions are also very likely to just dig the plants up anyway.

Conclusion

This ended up being much longer and more in-depth than I had initially planned, so I'm going to break it up into parts. The goal of this is also not to provide a specific care guide or parameters you should absolutely hit when keeping scorpions, but rather to give you a framework to decide what is important, what is scientifically supported, and what the *goal* should be. The next sections will cover scorpion diseases and first aid treatments, as well as some general misconceptions and other things I want to draw attention to. Thank you for reading, and I hope this was helpful!

Further Reading and References:

All Scorpion Archives

r/Scorpions

Aquarium Breeder Care Guides

Invertebrate Medicine 3rd ed.

The Spiral Burrow: Website and Book

Scorpions

Scorpions of the World