Terrestrial Isopod Care
Written by Shadoe Haffner, AKA GodzillaHermitCrab on deviantart, AKA wolfnipplechips on hermitcrabassociation
Isopods can be kept as pets and/or raised as janitors and food for your hermit crabs. They will not harm your crabs, as they would rather feed on decaying matter left in the tank, and only burrow an inch or so in the soil. They help displace pests such as mites and flies, and they help prevent mold by cleaning up leftover organics. Each one (if lucky) will live a few years, and reproduce many times over his/her lifetime.
A colony of just a few isopods will quickly become a colony of hundreds in just a short time if the conditions are good. You want to have a nice sized container that is capable of maintaining a high humidity. A glass tank of 10 gallons will do very nicely, but you can also use acrylic, or plastic as well. Storage totes that have locking lids are usually fair priced, portable, and work well. A ventilated lid is needed to prevent mold growth, but do keep an eye on humidity to make sure it doesn’t drop. Air out poorly ventilated containers daily.
- Tank: 3+ gallons for a breeding colony
- Temp: 70-85F depending on species
- Humidity: 60-90% depending on species
Keep a spray bottle handy with dechlorinated water. Spray at least once a day. Water conditioner can be found at your local pet store or online. If you have a more tropical isopod species, you may need to purchase a heat source such as a UTH placed on the side of the tank, in which case you will probably want to use a glass tank. Most will not need a heat source if your house is kept at 70F or more.
A decent set up in a Sterlite container.
Substrate doesn’t matter very much. They do fine on just about anything. You can use anything from straight sand to a mix of ten different things. I like to use a mixture of a few different things in mine. I mix sand, eco earth, worm castings, leaves, and occasionally sphagnum moss.
- It should be in 1-3 inches deep.
- It should be moist.
You should replace half (not all) the substrate every year or so. This will probably mean throwing out some babies, unfortunately, but it needs to be done.
Isopods like to hang out under bark or logs, so an overturned item of some sort will provide a daytime shelter. I usually have a main substrate, then I place a large piece of bark with an elevated end on the substrate (will make a nice humid hideout). I also add small chunks of bark around. Then I add about 1 cm thick layer of crushed leaves. This will be their bulk food source as well as a hiding place. Then I might add a moss layer on one end to help with humidity. You can get as fancy as you want.
Woods/leaves they like:
Make sure that if you harvest from these plants, you do so in an area free of pesticides and pollutants!
Isopods hiding out on some maple bark.
Isopods are detritus feeders, meaning they eat decaying plant and animal matter. Your layer of decaying leaves and wood will provide a lot of food, but you also can feed them a variety of other things to keep them healthy.
- Most fruits and berries
- Most veggies
- Dead insects such as crickets or meal worms
- Fowers and bee pollen
- A calcium source like cuttlebone, egg shells, or crushed oyster shells *this is a MUST for healthy exoskeleton growth!*
Make sure to keep an eye on these food items in the tank. When they start to mold, remove them.
An isopod eating squash.
All water that goes into your isopod tank needs to be dechlorinated! As mentioned before, you can find water dechlorinator at your local pet store or online. Isopods do not need a dish of water. When you spray once a day, they will get their water from that, or if you feed fresh fruits or veggies, they can also get some water from that.
Isopods molt, just like your hermit crabs! Well, sort of. Isopods shed their exoskeleton in two parts. First the front, then the back. This can happen hours or a couple days apart. You don’t need to do anything special for them when they molt. They will often eat their molts, but not always.
An isopod shedding the anterior end of its exoskeleton.
It is not an easy task to tell male isopods from female. You will only have to do this if you’re trying to selectively breed them for a certain trait. The most accurate way is to hold them between your fingers, upside-down, and look for modified pleopods. Only males will have them. Since it’s hard to describe, here are some photos.
The arrows are pointing to the modified pleopods on the male.
It’s easiest to sex larger individuals, and it might also be easier to use a decent camera instead of your eyes alone. If you still can’t tell male from female this way, there is one other way, and that is by their shape. Females will have rounder, larger bodies. Males tend to have longer bodies, and are usually slightly smaller.
Mating and Pregnancy:
Isopods can start making babies when they are at about half of their adult size. Isopods mating may look a bit like a fight. The male will grab the female, sometimes biting her.
Gravid females will carry their babies for about 3 weeks weeks before they are ready to bust out and live their own lives. The babies grow on the underside of the female (see photo below).
When the babies are born, they will be tiny and white/yellow colored. Don’t mistake them for mites! As they grow, they will darken to their adult color.
You can harvest your own isopods if you live in their range. Go and look under logs, rocks, and leaves to collect them. If you are going to start a colony, get at least 15 individuals. One thing to look out for are isopods infected with a virus called iridovirus. Infected individuals will be easy to tell apart. If the isopod is bright blue or purple, leave it be! This virus is contagious to other isopods and is fatal. You can also order starter colonies online if you can’t or do not want to harvest them on your own. If you order online, you have a choice of many different species. Be sure to read up on care of that specific species as they may prefer different temps depending on their native range.
Adding isopods to the crab tank:
Once your colony has started breeding, and you see many babies, juveniles, and adults (Usually takes a few months), move some of the adults into your hermit crab tank. If you have a big tank (40+ gallons), wait to move at least 100 over to your tank. If it’s smaller, move at least 50. The isopods may breed if the tank offers good conditions, and some may get eaten by the occupant(s) of the tank. Make sure the isopods have places to hide in the tank. They will come out at night to find scraps of food left over by your animal(s). Mine usually occupy wood decor in the tank, especially cholla on or near the substrate. I also add some moss nearby for any babies.
Adding isopods to the tank of your desert reptile/invertebrate pet:
Adding isopods to a desert environment is a little tricky, but can be done. The isopods NEED high humidity in order to breathe, so you can turn one corner of your desert tank into a little isopod oasis. Place your animal’s water dish in one corner, and place a piece of wood (maple/oak/birch/beech) behind it and cover it with some moss or leaves so that your isopods can live behind this water dish during the day. At night, they will brave the low humidity for a while to eat scraps, and return to their little desert oasis during the day. Just make sure to keep that corner moist, and they should be fine.
Common Questions and Concerns:
I added isopods to my tank, but I haven’t seen them in weeks.
-It’s possible they’re just hiding, but it’s also possible that you did not add enough. They can be a bit touchy at first, but once they’re established, you should be seeing them fairly often. You can try adding more.
Do the isopods eat mold?
-No. They eat the things that would otherwise grow mold. The help prevent it, but they do not get rid of it.
My isopods are taking forever to breed.
-It takes them a few months to really get started breeding in your breeding tank. Give them some time. If you’re not seeing any pregnant adults or babies and you have at least 15 adults, try increasing the temperature by a few degrees if possible.
Will my hermit crab eat the isopods?
-Yep! If they can catch them. I have seen several hunting techniques from an active pursuit to a sit and wait technique.
My isopods are dying for no reason and I am doing everything right.
-Diebacks are fairly common. It’s possible they got too numerous for their food source or limited space. try feeding more or moving them to a larger container. It’s also possible you got a bad batch and they have some sort of disease or parasite. If you can’t keep them alive, start fresh.
My isopods are eating each other!
-Cannibalism is fairly common in captive populations. It can’t really be prevented, but just remember to feed animal protein to help.
Will they hurt molters?
-I don’t believe so. They can only dig a small ways into the soil. Even in a surface molt, crabs are pretty well protected. Isopods generally prefer easy meals.
Do they help with mites?
-Yes and no. They help tremendously with food mites if you have a huge population of isopods in your tank. They displace the mites by eating leftover food. They will not help much with parasitic mites.
What are those white things on their underside?
Common wild species in the U.S.:
Armadillidium vulgare: These are the shiny ones that can roll up into a tight ball. Their color can be dark blue, grey, black, and even green. The mature males will usually be a solid colors, and the females will usually have some sort of green or yellow markings.
Armadillidium nasatum: They can roll up, too, but not as tight as A. vulgare. Their color can range from white to red to orange to grey, but grey with light grey-white markings are most common.
Porcellio scaber: Their color can range from dark blue to grey usually, but other color morphs do exist. Some may have an orange or light grey outline on their bodies.
Porcellionides pruinosus: These are extremely fast runners. They are a bit smaller in stature, have striped antennas, and have an iridescent sheen to them. They almost look dusty. Their color ranges from orange to grey to purple. Most look grey-ish purple. They are able to stand low humidity well.
Trachelipus rathkii: They are sometimes hard to distinguish between P. scaber, since they have the same body shape, but T. rathkii is distinguished by its 5 pairs of gills (compared to 2 in P. scaber). They also are usually mottled in color with orange and yellow commonly showing up.
Philoscia muscorum: These are medium sized, fairly fast, and are easily distinguished by their dark head and strange posterior shape. They are usually brown or yellow in color, mottled.
Porcellio spinicornis: These are fairly large in size, and look even bigger with their extended sides. They are usually grey or brown with a yellow or light color pattern going down the middle.
Photo from http://bugguide.net/node/view/106483
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