Why small works
A sling does not need an adult-sized enclosure. A compact container makes it easier to find the spider, remove prey and monitor feeding and moulting. It also makes it easier to maintain the right moisture level without creating a huge wet area.
Escape-proof ventilation
The ventilation holes must be smaller than the sling can squeeze through. Tiny spiders exploit gaps that look impossible from the outside. Test lids, seams and feeding ports before the spider goes in.
Space by lifestyle
Terrestrial slings need floor space and substrate, arboreal slings need a small vertical retreat and anchors, and fossorial slings need surprising substrate depth for their size. Do not use one deli-cup setup for every species.
Water
Small slings can use tiny water dishes such as suitable bottle caps or micro dishes when practical. Moisture-dependent slings also need carefully managed substrate moisture because small containers dry quickly.
When it is too small
Rehouse when the spider has little room to turn, the retreat fills most of the enclosure, maintenance becomes difficult or growth makes the ventilation and access unsuitable. Do not rehouse purely because a set number of weeks has passed.
When it is too big
A larger enclosure can work, but it becomes a problem when the sling cannot be monitored, prey disappears or there are unsafe gaps. Choose an enclosure for control and observation, not for how impressive it looks on a shelf.
Why sling care changes quickly
Sling husbandry is temporary by definition. A container that is perfect this month may be too small after two good moults, and a moisture routine that works in winter may dry too quickly in summer. Check the enclosure after each moult instead of assuming the original setup will remain suitable until the spider becomes a juvenile.
Small changes matter more at sling scale. A ventilation hole that would be irrelevant to an adult can be an escape route, a few millilitres of water can alter most of the substrate, and one oversized prey item can dominate the whole enclosure. Keeping the setup simple makes those variables easier to control.
The five-point sling check
For a quick routine check, ask five things: is the lid secure, is the spider able to retreat, is the moisture appropriate for the species, is drinking water available in a suitable form, and is there any live prey that should be removed? If those basics are right, the sling usually needs less interference rather than more.
Do not dig up a hidden sling merely to prove it is alive. Sealed burrows, webbed retreats and periods of food refusal are normal around moulting. Keep records and let the spider reappear on its own unless there is a concrete reason to suspect flooding, injury or another genuine enclosure problem.