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As a hobby-specific business we refer to these little critters as "Isopods", although that term is incredibly broad outside of this context! Isopods are a massive order of crustaceans which contains over 10,000 different species. In this article we'll be focusing on information pertaining to the terrestrial varieties often kept in captivity as part of a biologically active live vivarium ecosystem. We'll discuss the differences between Genres (sub-categories) available in the hobby, how to care for them, and what makes each type unique. Because each variety is fairly similar in overall requirements we've decided to write one simple article rather than multiple tiny ones catered to specific species. Please keep the slight differences in care requirements in mind (described below) when setting up the home for your particular variety.
Isopods are detritivores (consumers of dead organic material), and are an important part of most ecosystems they are a part of. In nature, the species of Isopods we care for are typically found in leaf litter, under wood & rocks, and in other moist areas. The word Isopod is derived from Greek meaning "Equal Foot", since they have an equal number of feet on each side of their body. Isopods belong to the subphylum of Crustacea (Crustaceans), which makes them more closely related to Lobsters & Crabs than Insects. The vast majority of Isopods found in this hobby seem to belong to the terrestrial suborder Oniscidea which contains over 5000 known species. There are a few dozen different species and varieties found in the hobby (only a small percentage are represented at usmantis), with each having it's own particular traits. In our experience, Porcellio, Armadillidium, Nagurus, and Trichorhina are some of the most commonly kept Genres of Isopods in the hobby.
Reptile & Amphibian enthusiasts can watch for certain visual cues to tell if an animal is healthy or sick. The same goes for Isopods, believe it or not! An Isopod's rate of travel depends on a number of factors including temperature (70-85°fpreferred), humidity (55%+ R/H preferred), amount of light (darkness preferred), and even "tightness" within an area. When conditions aren't favorable due to any of the aforementioned factors, an Isopod will move quicker until it finds a more comfortable setting, where it will slow back down. This practice of changing speed of movement based on an external stimulus is called orthokinesis, and is an interesting thing to observe. Isopods are positively thigmotactic, meaning they prefer (and in this case will seek) contact with surrounding objects to help them conserve moisture & prevent dessication. This behavior is why Isopods can often be found grouped tightly together in a social practice called aggregation. When they are in motion, Isopods find their way around using turn alternation, which essentially means means they'll instinctively turn right & left in quick succession to navigate. This is thought to ensure that an individual is less likely to circle back & become prey when threatened, and will be more likely to eventually find a favorable condition during casual movement. When it comes to Isopods, slower movement & finding groups huddled together are both healthy behaviors to observe. On the other hand if they are actively moving around at a fairly rapid pace (without first being disturbed), there may be something less than ideal going on with their environmental conditions. It's worth keeping an eye on them, since observing & understanding their behavior can act like a bellwether for certain problems which can occur in a live vivarium.
We've received a few emails from new & potential hobbyists who have questions regarding aggression & other concerns with Isopods. It's worth mentioning that none of the species we work with is capable of inflicting a bite on a human, and we've never seen Isopods display aggression toward any Reptile or Amphibian cohabitant species. The only concern which is remotely linked to aggression would be interspecies competition. We recommend keeping just one variety of Isopod per enclosure to ensure populations don't end up competing for resources, since most small environments would ultimately end up with just one species thriving in the long run. On the other hand, housing one species of Springtail with one species of Isopod is considered common practice.
The care strategy we recommend depends on how the Isopods will be kept, so identifying the two different methods of care is important. We recommend keeping these definitions in mind while reading through the rest of the article. These aren't scientific classifications; just an easy way to define & separate two styles of husbandry.
Most of the Isopods we sell are utilized as detritivores in a live vivarium environment's food web. (Enthusiasts sometimes call Isopods part of a "Bioactive Terrarium Cleanup Crew") In this situation, a live vivarium is designed for another species of animal like an Amphibian, Reptile, Arachnid, or Insect. Isopods & Springtails are introduced to the enclosure to help the living environment thrive. (We'll get into this in more detail later) When Isopods are kept in this way, we consider them secondary inhabitants.
Over the past few years, keeping Isopods as pets has become more common within both the vivarium & exotic pet hobbies. Isopods are unbelievably low maintenance by comparison to just about anything short of a houseplant, and they make a great quirky pet in a variety of different settings. If a species of Isopod is kept as a pet, or the "main attraction" within an enclosure, we consider them the primary inhabitant.
There are many ways to ensure Isopods can thrive in captivity, and we'll describe the foods & methods which have worked best for us over the years.
We rely on boiled leaf litter as the only constantly available primary food source, and ensure plenty is available at all times. As the Isopods fragment & devour the leaf litter we do our best to replace it ASAP. Hand-crushed magnolia leaves are a great choice since they are inexpensive, frequently available, and thicker than most others on the market. Live Oak and Sea Grape leaves also work great. All leaf litter should be sterilized (boiled) before introduction to prevent contamination from any possible external pathogens.
Plants shed leaves, many types of mycorrhizal fungi produce mushrooms, and some algae creates biofilm. Each of these things occur naturally in a well designed live vivarium, and are just a few examples of something which can eventually be consumed by Isopods & other microfauna in a live vivarium environment.
If Isopods are kept as secondary inhabitants within a vivarium housing a more complex species, they'll have even more of a naturally abundant food source courtesy of the animal's waste. Nutrients will naturally pass from the primary inhabitant down into the microfauna populations, where the waste will be fragmented & devoured. (More on that later) For this reason, vivariums in which the Isopods are a secondary inhabitant are less likely to require additional nutrient rich foods.
If an environment doesn't offer enough nutrients for the Isopods to thrive naturally, offering nutrient rich foods may be beneficial. This is most commonly required when Isopods are kept as a primary inhabitant of an enclosure (since there won't be any added nutrients from the animal's waste), or when Isopods are kept in an enclosure where they are frequently preyed upon. (Pumilio dart frogs for example) We offer tiny amounts of Repashy Morning Wood and Repashy Bug Burger 1-3X weekly, depending on the size/maturity of the colony. Both of those diets provide calcium as well as a slew of other vitamins & minerals. Our goal is to offer only what the Isopods will devour within 36-48 hours at each feeding, and only offer more food once the original amount has been gone for 1-2 days. If an abundance of nutrient-rich food is left out for too long, it may attract unwanted guests like Fungus Gnats. (Harmless but annoying, more info in VC102) For this reason, it is absolutely critical not to offer too much food at one time. To start, we recommend adding a pencil eraser sized portion of either Repashy Product and checking to see how quickly it's devoured. From there, it should be easier to get an idea of exactly how much a specific culture will devour within a given time. It's better to feed a little less than to feed a little too much.
We recommend against feeding Isopods fish flakes, rice, cereal, and dog food. After experimenting with all three in the past, we found mostly negative results in comparison to our usual method described above. Fish flakes seem to quickly attract detritivorous mites, uncooked rice seems to harbor & allow for the proliferation of flying pests, and both cereal and dog food seemed to slow the growth of the cultures while attracting unwanted guests. We've seen some commercial products being marketed towards a "once and done" solution towards feeding Isopods within a vivarium. We wouldn't recommend a practice like this, since long-term abundances in nutrient rich substances can result in various opportunistic pests proliferating within the live environment.
Virgin cardboard has been used as a source of cellulose within the hobby for years. Isopods digest cellulose as a part of their natural diet, so this practice makes some sense but the chances of introducing glue & ink is too high for us to risk this at usmantis. Some enthusiasts recommend adding some calcium within the substrate through powders or cuttlefish bones, but we've never found this to be necessary while using the already fortified food and Substrates.
Most basic style enclosures are built by Isopod enthusiasts, breeders, or by those in an educational setting. These are a little harder to maintain than a live vivarium, but are far cheaper & simpler to create.
We recommend providing an enclosure with at least 6 quarts in overall volume (about 1.5 gallons) to start a small colony from one of our Isopod starter cultures. As the population grows, the size of the container can be increased considerably. The Isopods we work with won't readily climb clean glass or plastic containers with vertical sides. A Sterilite container, small aquarium, or tiny glass terrarium would work great for this purpose depending on your aesthetic goals. Providing a small vented area on the top of the enclosure is especially important, considering adequate airflow has proven to be highly beneficial to Isopods in captivity. The ideal size of a vent depends on your ambient conditions, but we personally add a 2in vent on 6 quart (1.5 gallon) containers, 3in vent on 16 quart (4 gallon) containers, and two 3in vents on 28 quart (7 gallon) containers. All vented areas should be covered by fine screen mesh to prevent unwanted guests from joining your Isopod colony. If you have any of our usmantis Screen Separator lying around, we'd recommend using it. Other options include more expensive 2-micron filters, and less expensive coffee filters. We use our non-toxic black silicone as adhesive for adding screen.
We use & recommend V2 Vivarium Substrate mixed with boiled Leaf Litter for this purpose. The substrate is admittedly a little "over-engineered" for a simple enclosure like this, but it's the basis of all of our breeder cultures here at usmantis, and we've had great luck with it over the past few years. Substrate should be at least a couple inches deep, and a few inches away from the top of the enclosure. A thin layer of Leaf Litter is then applied on top of the substrate, with care taken to ensure it doesn't reach too far up the sides to allow for Isopods to escape. We recommend moistening the whole enclosure evenly at first as an easy baseline. Afterward, one end of every enclosure is kept slightly more dry than the other to allow the Isopods to naturally hydroregulate. We try to keep all of our Isopods between 73F-83F year-round. If your room temperature is significantly cooler, it may be worth purchasing an Under Tank Heater, and placing it on one side of the enclosure to allow the Isopods to thermoregulate. (We've got models available for both plastic & glass style enclosures!)
Maintenance & upkeep will involve adding more boiled & crushed leaf litter as the supply is eaten, misting every other day or so, and performing at least partial substrate changes every 4-6 months. Isopods kept in a basic enclosure won't benefit from the food described in the above "Natural Live Vivarium Detritus" paragraph, so it's critical to provide food from both the "Leaf Litter" and "Nutrient Rich Food" categories instead.
This section will illustrate in detail how to care for Isopods within a live vivarium environment, and what one can expect in terms of long term maintenance.
Isopods can play a critical role as detritivores within a live vivarium environment. They do a great job of helping to process fallen leaves and other detritus produced by co-habitants. The widely held belief that Isopods directly decompose waste within a live vivarium is actually a misconception. Isopods aren't responsible for decomposing these materials directly, but they do greatly contribute to the fragmentation of organic matter. (Essentially breaking things up by agitation, chewing and/or digestion) This process makes further fragmentation by Springtails and eventual decomposition through mycorrhizal fungi and microbes within the substrate more effective. In our experience, Isopods are more effective at quickly breaking-down larger bits of detritus than Springtails, which helps ensure waste is processed a little quicker than it would otherwise. Compared to Springtails, Isopods are also less prone to dessication (drying out) in an enclosure, which allows them to be a little more bold by climbing higher surfaces to reach things which might otherwise be missed. In our experience, Isopods also help to prevent substrate from compacting over time. The light & airy substrate mixture benefits mycorrhizal fungi, which is at least partially responsible for finally breaking organic matter down into elements which can be more easily absorbed by plants. Introducing Isopods to most vivariums is recommended, but is especially important when housing medium & larger species which will produce more waste.
We recommend adding Isopods to an enclosure after the substrate layers & main plants are added, but before the leaf litter has been set in place. It's important to add microfauna to a live vivarium as soon as it's planted, to ensure no opportunistic detritivores have a chance to establish themselves first. usmantis Isopod Cultures are 100% safe to pour directly on top of the substrate layer, and we recommend evenly spreading a cultures contents within an enclosure to avoid any high points. We don't recommend manual agitation (stirring it up) after it's been poured, since doing so may injure the fragile Isopods. After the Isopods have a moment to work themselves down into the substrate (they usually will pretty quickly), Leaf Litter can be added to the vivarium as the final touch. (The same procedure applies to Springtails)
With the Isopods added & vivarium finished, it's critical to allow both Springtails and Isopods at least 3-6 weeks to acclimate before adding inhabitants. We recommend waiting as long as possible, to ensure the Microfauna have plenty of time to establish healthy populations. We'd expect to find signs of Isopod activity throughout the leaf litter layers after about 3-4 weeks, where they'll be found feeding on the decaying leaves. Keeping the enclosure a little extra moist (75%+ R/H) during this time may be a good idea, to ensure they have the opportunity to reproduce as much as possible during acclimation. Even if your inhabitant species won't need it that humid in the long run, keeping it that way in the short term will help the Isopods get a head start before the primary inhabitant is introduced. This practice helps the plants, Springtails, and mycorrhizal fungi too!
All vivariums require replenishment of Leaf Litter over time, but it's extra important to remain diligent if Isopods are introduced. If Isopods are a secondary inhabitant species, additional food sources are not usually required considering the abundance of leaf litter, naturally shed plant leaves, and inhabitant waste which will be present. In some rare cases where there isn't enough available nutrients, adding very small amounts of nutritional food may be beneficial to an Isopod population within a vivarium. The enclosure should be misted daily, especially if the relative humidity of the enclosure drops below 60%. Very humid enclosures can be misted a little less often, with the primary goal being to ensure the substrate never dries out.
A good live vivarium substrate is a critical element which helps ensure Isopods can establish & maintain a population within an enclosure long term. Live vivarium substrate will sustain plant life, mycorrhizal fungi, beneficial microbes, and resist breaking down long-term. It should also remain airy enough to allow microfauna to travel freely from top-to-bottom within the substrate layer.
Odd as it may sound, Isopods actually make a great pet for a variety of different types of owners; not just exotic animal & plant enthusiasts. They are a great first pet for kids, a perfect way to build an interesting classroom display (Teachers might want to check out NSTA's helpful page* Ext. Link), and are even a good fit for an office or dorm room. Having a micro vivarium with plants & Isopods is an inexpensive, low-maintenance affair. Partial glass tops are strongly recommended to keep humidity up within both Aquarium & Terrarium enclosures. UVB lighting isn't required, and the most basic (i.e. inexpensive) recommended Vivarium Lighting solutions will do the trick. We recommend misting the enclosure at least once daily. The V2 Substrate which comes with our kits should last for years, and the only special instruction for an Isopod-only vivarium is crushing up some boiled leaf litter & mixing it into the substrate layer before the enclosure is finished. We try to keep all of our Isopods between 73F-83F year-round. If you need to heat your enclosure, we recommend placing an Under Tank Heater on the side to increase temperatures. Beyond that, an Isopod vivarium is set up just like any other.
Isopods are technically a suitable prey item for a ton of different small Reptiles & Amphibians. It goes without saying that we recommend keeping your primary inhabitant (whatever it may be) very well fed. Doing so will usually help to minimize (or at least decrease) Isopod predation, from what we've seen. An inhabitant which eats a few Isopods here & there won't usually damage an established population within a vivarium, since the colony within should be able to keep up by producing new offspring. It's possible (although rare) that certain species of animal may more heavily prey upon the Isopods, which can eventually lead to a dwindling microfauna population. This is a more common problem for species like Dart Frogs, and it may sometimes be necessary & beneficial to add a small starter culture every so often to ensure the numbers stay high. Keepers of Ranitomeya and (especially) Oophaga Dart Frogs regularly add Isopods to their enclosures, since freshly morphed froglets require (or at least strongly benefit from) a steady diet of Isopods. We recommend Dwarf Isopods for vivariums which will be housing smaller inhabitant species.
Larger inhabitant species create a higher volume of waste, and this generally requires a more effective means of organic fragmentation to prevent it from accumulating. For this and many other reasons, having an established population of Isopods is especially critical when housing medium & large inhabitants. A healthy population of microfauna will be better able to keep up with the fragmentation of organic waste, which makes it easier for the mycorrhizal fungi & microbes to break things down into elements which can be more easily utilized by plants. (This may be an oversimplification, but you get the idea!) Consequences of not having a healthy microfauna population include issues like waste accumulation and the establishment of unwanted detritivore species (fungus gnats, etc). Dwarf, Porcellio, or Armadillidium Isopods are all fine choices for medium & large inhabitant species.
If you are looking through this section in hopes to find the type of Isopod which will be visible most often in a vivarium, it's important to understand that the environmental conditions will play a major role. Each species is generally most active at night, but we've found that they will be more active during the day if conditions are especially humid, and a darker (shadowed) area of the enclosure is made available to them. If an enclosure is particularly dry with no shaded spots for the Isopods to explore, it's very unlikely that they'll come out during the day.
We carry and work with a handful of different species & morphs, but there are tons moreavailable in the hobby. Hobbyists all over the place seem to be working with new & exciting morphs every year, and we're looking forward to learning more & working with different varieties as time goes on. In the meantime, we'll summarize the three categories we use to keep track of Isopods
These are the largest Isopods we work with, approaching 5/8in in length. Species in this genus are able to roll into a ball when they are disturbed, which helps to protect their soft underbelly while only exposing their harder shell. This behavior has earned them the common names "Roly Poly" and "Pillbug". Unlike our smaller varieties, these reproduce significantly slower and are far less common in the hobby. Although they perform the same function as any other Isopod we carry in a live vivarium environment, Armadillidium species seem to be more commonly kept as pets by invertebrate enthusiasts. If they'll be used as a detritivore within a vivarium designed for another primary inhabitant, we strongly recommend allowing extra time to ensure they can establish a large enough population. Otherwise, these are a great choice for those who are looking to build a micro-vivarium with Isopods as the primary inhabitant