Tarantula Death Curl vs Molting: How to Tell

Your tarantula is on its back, legs in the air, and it is not moving. Your stomach drops. Before you do anything, read this first, because the single most important thing you can do in this moment is often nothing at all.

A tarantula lying on its back, legs pointing up, resting on a small mat of webbing it laid down beforehand, is almost certainly molting. This is normal, it is healthy, and it can take anywhere from several hours to a full day. During a molt you must never disturb, poke, flip, or try to help the spider. Interfering with a molt is one of the most common ways keepers accidentally kill an otherwise healthy tarantula. Turn off bright lights, keep the room quiet, and give it time.

A death curl is a different picture entirely, and knowing the difference is the whole point of this page. In a real death curl the legs are curled tightly underneath the body, drawn inward like a dead spider clutching itself, and the tarantula is usually upright or on its side rather than flipped onto its back. It points to a genuine emergency, most often dehydration, cold, or a bad molt, and unlike a molt it is something you may still be able to reverse if you act fast.

Most likely causes of a real death curl

1. Dehydration (by far the most common). This is the big one, and the one keepers most often miss. A great many tarantulas thought to have starved actually died of thirst. Tarantulas can go a remarkably long time without food, but they need water, and a shallow water dish should be available at all times, even for species kept on the dry side. If your spider is in a curl, dehydration is the first thing to assume and treat.

2. Too cold. Tarantulas are ectotherms and slow down badly when temperatures drop, and sustained cold can push a spider into a curl. Most common pet species do well around room temperature in the low to mid 70s Fahrenheit, and a spider that has been sitting in a cold room needs gentle, gradual warming, never direct heat.

3. Post-molt complications. A molt that went wrong, where a leg got stuck or the old exoskeleton did not release cleanly, can leave a spider weak, curled, or missing a limb. This is a delicate situation and often needs the ICU approach below.

4. Dyskinetic syndrome. This causes jerky, uncoordinated movements and an inability to right itself. It is poorly understood, difficult to treat, and worth knowing about so you do not confuse it with a simple molt.

5. Old age. Tarantulas do reach the natural end of their lifespan, and mature males in particular live only a short time after their final molt. Sometimes a curl is simply the end of a long life.

6. Pesticide or chemical exposure. Tarantulas are extraordinarily sensitive to insecticides, flea treatments, fumes, and cleaning chemicals, and exposure anywhere in the home can be fatal. If you have used any of these near the enclosure, treat it as a likely cause.

For a fuller picture of normal molting, feeding, and handling, our tarantula care guide covers the routine side of keeping these animals well.

What to do tonight

First, decide which situation you are in. If the spider is on its back on a web mat, and especially if you can see any slow movement of the legs or fangs, it is molting. Do nothing. Keep the enclosure humid, the room dark and quiet, and check again in the morning. A molt can take most of a day, and patience is the correct response.

If the legs are tucked underneath and there is no web mat, and the spider is dehydrated or has been cold, the standard first response is the ICU method, aimed at rehydration. Line a small, clean container with a paper towel dampened with dechlorinated water, moist but not flooded, with no standing water the spider could drown in. Place the tarantula inside with its mouth area near the damp surface, keep it humid and gently warm at room temperature, never on a heat mat or in direct sun, then leave it in a quiet, dark spot. Recovery, when it happens, is slow and measured in days, so avoid handling.

One rule applies right after any molt: never feed for at least a week. A freshly molted tarantula has soft fangs and a soft exoskeleton, and a live feeder insect can injure it while it hardens. Wait until the fangs have darkened, keep water available, and only then offer food.

Throughout, keep a record: the date, whether it looks like a molt or a curl, temperature and humidity, when you last saw movement, and anything you tried. The VetGPT app helps here - snap a photo, log the behavior and enclosure readings, and get an AI read on urgency plus a trend over time. It does not diagnose your tarantula or replace a vet, but for an animal so easily mistaken for dead when it is only molting, a clear record steadies your hand. Learn more on our exotic pet care page.

Finally, invertebrate-savvy vets are rare, so find one before you ever need one. A small number of exotic vets treat tarantulas, and knowing who to call, with your records ready, matters most in exactly the moment you are in now.

Common Questions

How do I know if my tarantula is molting or dying?

A molting tarantula lies on its back, legs pointing up, usually on a web mat it laid down first, and it can stay that way for several hours up to a full day. A death curl is different: the legs are curled tightly underneath the body like a dead spider clutching inward, and the spider is usually upright or on its side rather than deliberately flipped over. On its back with a fresh web mat means molt. Legs tucked under with no web mat means distress.

Should I help my tarantula molt?

No. Never poke, flip, move, or try to help a molting tarantula. Interfering with a molt is one of the most common ways keepers accidentally kill their spiders. Leave it undisturbed, keep the enclosure humid, and give it 24 to 48 hours to finish. Only consider intervening if a molt is clearly stuck after 24 hours or more, and even then research the situation carefully first.

What causes a tarantula death curl?

The number one cause is dehydration, and many tarantulas thought to have starved actually died of thirst, so a water dish should always be available. Other causes include the enclosure being too cold, complications after a molt, dyskinetic syndrome, old age at the natural end of the lifespan, and exposure to pesticides or chemicals. If a spider in a curl is still responsive, the ICU method aimed at rehydration is the usual first response.

When can I feed my tarantula after a molt?

Wait at least a week after a molt before offering food. A freshly molted tarantula has soft fangs and a soft exoskeleton, and a live feeder insect can injure it while it is still hardening. Give it time to firm up, keep water available, and resume feeding only once the fangs have darkened and hardened.