Humidity

There is a great debate that has been raging for decades in reptile-keeping circles, do we need to mimic the wild environment of our animals, and I'm including isopods in that statement. The other side to that debate is that animals are variable, and other than some unusual species most will thrive in a healthy middle ground.

You are hopefully looking to buy isopods that are captive-bred and sold from here in the UK. It's no use finding isopods for sale, doing your research on the correct species, and not seeing that pay off in terms of a thriving colony. So what is humility and why is it important?

What is humidity?

Humidity is the amount of water vapour in the air. The hotter the air the more water vapour it can hold. So if you have an enclosure at 20ºC, that can hold twice as much water vapour as the same enclosure at 10ºC if everything else remains the same.

Measuring humidity

Reptile and other exotic keepers tend to use relative humidity. That is the percentage of water vapour in the air for that temperature. Compared to how much that is theoretically possible. Measuring humidity is a lot more difficult than the cheap humidity gauges would have you believe.

You can have 100% humidity in a vivarium that is cold, but that isn’t as much water vapour as a warmer vivarium at say 60% humidity. The two numbers are linked, and we have to ensure that both are dealt with.

Controlling humidity in a vivarium or terrarium

The first step is to find and establish the correct temperature for the species you are keeping. Cubaris sp. such as Panda Kings or Rubber Duckys generally come from warm tropical regions, whereas Moo Cow Isopods thrives in slightly cooler conditions. As the temperatures lower the amount of water vapour in the air will naturally drop. This is the reason you might see condensation on the glass or sides of your enclosure in the morning after a slightly cooler night. The cooler air holds less energy, and the water vapour condenses on the colder surfaces.

 

There is nothing wrong with a cooler nighttime period. Even in the tropics, the air temperature will drop overnight. That wonderful time when the mugginess of the day gives way to the refreshing evening air. Just make sure that you don’t let it fall outside of the safe range for your isopods.

To help keep the humidity levels in the correct range you want a substrate that will retain moisture, and release it as the air loses water vapour and dries out. For isopod keepers, the good news is that leaf litter holds humidity well, but there are a whole host of other substrates to consider, from mosses to coconut husks, and other natural moisture-retaining substrates. Be careful that they haven't been treated in any way as some plant products have to be treated for pests before being imported.

Why is humidity important for isopods?

Isopods moved out of the ocean in evolutionary terms without lungs in the way we think of them. Ours are internal, giving our body a chance to regulate things, such as the humidity of the air before it hits our lung sacs. Isopods have pleopodal lungs, these are external for most species of isopods, meaning that their lungs are exposed to the outside air with no chance for the body to add humidity before it comes into contact with the features designed to get oxygen into the body.

For all animals, the humidity can influence body temperature, how wet or dry their skin is, how their eyes function, and so much more. Isopods are no different.

Creating a slice of nature

 Looking just at humidity, how would we a keeper, many thousands of miles away from the natural habitat for our animals, know what the correct humidity is? Especially given we know so little about many of the species arriving into the hobby?

Climate vs. Microclimate

Climate is the average weather conditions for a particular area over a long period of time. A microclimate is a small area that has different conditions from the surrounding area.  

We need to consider both of these, the climate in Thailand is hot and humid, but is that going to be the same in a large cave, or a small cave? The weather in the UK tends towards cold and wet with moderate humidity, but again is that true in a cave deep underground? In fact, the two caves may share more similarities than we might think. In the leaf litter on the forest floor, there is yet a different set of conditions. It is in these microclimates that we find our isopods.

Hallaniyat Island 'Oman' Isopods are a great example, their habitat is famed for being dry and barren, but even the driest deserts have climate shifts and microclimates. These isopods are generally nocturnal, coming out in the less-drying nighttime air. Spending the day in the crags and rocky piles that dot the landscape. Just like a plant pot on your back patio will harbour a damp area even in the height of summer, there will be pockets of higher humidity. But beyond that the annual monsoon season means that 6 months of the year fog rolls in off the ocean, increasing the humidity for at least parts of the day.

Many of the desert-dwelling isopods take things a set further, digging burrows to hide in during the heat of the day. Once night falls the air cools and falls, the water vapour condenses out in the depths of the cooler burrow, giving them moisture for hours and even days to come.

A healthy medium

Many species can survive and thrive in some sort of healthy medium, but it's well worth creating an environment to allow them to thrive. Let's be honest you're spending time and money on buying and keeping isopods, and all the other inhabitants of your vivariums or terrariums. Spend the time to get things right before you add any inhabitants, that way it will be a lot less stressful in the future.

 

We don't tend to worry about the nitty-gritty of isopod care when we buy them. But consider how much money you can save in the long term by breeding your own isopods from foundation stock. Get the care right and have a look at some of the rarer isopods we stock. A small group can grow into a large colony soon enough.

  

Gradients

There is another option, that I think more keepers need to consider. Gradients. That can be along the length of an enclosure, or as you go down through the top levels of the substrate. Plants will allow some areas to be more humid than others.

 Let's look at a reptile vivarium, good practice now for a lot of species is to have a temperature gradient, with a warm and a cool end. That means that the air at one end is being warmed more than the other, meaning that the humidity in real terms is higher at one end than the other. Isopods can therefore choose where they want to be in terms of temperature and humidity. Now let's not put a species that likes drier conditions in a vivarium that ranges from 70-95% relative humidity. But creating a gradient gives you the peace of mind to know there are safety margins in all directions.

Overall

Do your research so you know the correct humidity range for the species you are keeping, ensure you have a good quality substrate that mimics their natural environment, if suitable have a drainage layer, and mist your enclosures at regular intervals. Use a good quality humidity meter to measure the levels, and you'll be on your way to happy and healthy isopods, that will breed regularly.