Humidity and Jumping Spiders

Humidity in their natural habitat

Florida has an average humidity of 74-85%, with warm, damp mornings and a lower humidity in the evenings. This is due to Florida being a peninsula with large areas of vegetation rich wetlands.

Humidity is very important for Jumping Spiders

Not only are they accustomed to the harsh sunshine and high temperatures of Florida, but they thrive in the oppressive amount of humidity. Their exoskeleton is kept in tip top shape, the extra fluid needed for moulting is readily available as dew in the morning, thunderstorms in the evening, and well hydrated prey. Most keepers a well aware that a spider who has worrying health symptoms have a better chance at survival if they are moved to a smaller enclosure lined with damp kitchen roll or tissue (often called an ICU) because a higher humidity can help many health issues. It should be easy to see how important it is that this helpful humidity is recreated in their every day enclosure for their health and happiness.

The Exoskeleton

The exoskeleton on a jumping spider can become dry and uncomfortable with low humidity, and the setae (the sensing hairs on a spider) are easily worn away. Without these hairs a spider will not only lose the sense of smell and vibration, but it can greatly hinder hunting.

The small gripping tarsal hooks on a spiders feet that enable it to climb are likely to become brittle and easily damaged, meaning the spider can no longer climb. Although a lot of these issues can be common for an older spider, they present much earlier when jumping spiders are kept in dry enclosures.

Silk Glands

Humidity is also very important for silk production. Silk glands produce liquid silk proteins that quickly dry as it is is spun into sticky silk threads which keep jumping spiders safe by acting as a safety line should the spider fall. In dry environments this silk can lose it's effectiveness meaning it will no longer anchor and catch a falling spider. Lack of humidity is also to blame in most cases of silk impaction, when the liquid silk is no longer extruded from the spider and is often fatal.

Moulting

A spider due to moult will show signs of increased thirst because extra fluid is needed to help them physically moult, but drinking more is not enough on it's own as moisture can be lost through the exoskeleton in dry environments. Fluid is pumped around the spider, between the old exoskeleton and the new soft one beneath, allowing the spider to slip itself free of their old skin. Afterwards, the spiders circulatory fluids (called haemolymph) starts pumping again. It pumps through the spider stretching out of the post-moult death curl, and inflating and stretching the spiders new exoskeleton which is how they grow in size. A lack of humidity in the air can cause the old exoskeleton to be too hard to break free from, or cause the new one to harden before they are fully free of the old one.

How to help humidity in a jumping spider enclosure

You want the humidity inside their enclosure to be between 70 - 80%. Misting an enclosure twice a day can only do so much for the humidity, how you decorate your jumping spiders home can really make a difference.

Decorations

Wood, cork bark, and soil based substrates absorb and release water slowly, this boosts the humidity inside a jumping spiders enclosure for an extended period of time. Plastic décor and fake grass doesn't absorb water, it simply dries off of them quickly, so an enclosure that has ONLY these elements will struggle to keep a safe humidity. A soil based substrate should be the first addition to any jumping spider enclosure, coco fibre doesn't offer the same slow moisture release as soil based substrates and is therefor not suitable to be used as a humidity-friendly substrate.

Live Plants

I have nothing against the humble and versatile silk flowers and plastic plants, I actually feel they can add colour and personalisation to any enclosure. Yet if you really want to make your jumping spider feel truly at home, then nothing beats a live plant. I can hear the sounds of people fretting about bioactive set-ups and the complicated concept of custodian isopods, but fear not, a planted enclosure does not have to be bioactive. You can still get all the benefits of a natural habitat for your spider alongside the humidity boost by simply adding in a plant of your choice. They don't have to be reptile recommended plants and some are easy to remember when browsing your local garden centre because of their names: Spiderwort (tradescantia), or little spider plants (Chlorophytum). You can try Fittonia, peacock spike moss, even something as simple as supermarket cress will do the job. As long as the plants like being watered once a week, a does well in warm humid environments then you can let your creativity run wild. The enclosure does have to have a decent soil based substrate to keep your plan alive, coco fibre, once again, is not right for the job.

Hygrometers

These are amazing tools to help you track the humidity percentage in your jumping spider enclosure. They come in various shapes and size as a single unit that sits inside the enclosure. They can be brought from reptile shops or larger multipacks and single devices are sold on Amazon. When adding a hygrometer to an enclosure make sure that the device is either hanging or mounted on the side with good air flow around it. If the device sits on the substrate or on wood, it will display the humidity of that particular piece of decor, and not the humidity in the air of the enclosure.  You want to aim for between 70-80% humidity. It doesn't matter if this figure fluctuates throughout the day, and being over 80% isn't an emergency as the humidity will drop lower on its own, but check for large droplets of condensation and wipe the side of the enclosure if necessary. You can also add extra vents (or holes) to mmany enclosures. If the hygrometer is reading around 90% but there isn't any signs of condensation, you may want to check your hygrometer isn't touching any decor or substrate, or that you've sprayed it while misting. II have a Hygrometer review coming very soon, to help you choose. Keep an eye on the Arachnamoria Facebook page for update.

Heat mats help humidity

Heat mats aren't just to keep your spider warm, as counter productive as it might sound, keeping a jumping spiders enclosure at the right temperature can really help the humidity. As the enclosure warms, the moisture evaporates boosting humidity. A 7 watt heat mat, placed behind (not under) the enclosure, and attached to a thermostat will regulate the temperature so you don't have to. Read more about jumping spiders and heating here

Coming Soon

As we delve deeper into habitat-first care I will update this post with links to related posts such a how to get started with a planted enclosure, exploring bioactive set-ups, and how to forage for your own decor.