Bumps, Blemishes, and Other Skin Abnormalities in Tarantulas

In tarantulas, "skin" problems usually involve the cuticle or exoskeleton, not skin like a dog or cat has. Pet parents may notice bald patches, dents, raised spots, cracks, scabs, fuzzy growth, discoloration, or areas that look misshapen after a molt. Some of these changes are mild and temporary. Others can point to dehydration, trauma, infection, or a molting problem.

A very common example is a bald spot on the abdomen in New World tarantulas. These spiders can kick off urticating hairs when stressed, and the exposed area may look pink, tan, or dark. Darkening can also happen before a molt, so appearance alone does not always tell the whole story.

More concerning abnormalities include wet-looking wounds, leaking hemolymph, soft or collapsed body areas, white or fuzzy patches, or deformities after shedding. Tarantulas are especially fragile during and right after a molt because the new exoskeleton is soft. Falls, feeder insect bites, and handling injuries can cause serious damage during that window.

Because many different problems can look similar at home, the goal is not to diagnose your tarantula yourself. Instead, focus on what changed, when it started, whether your tarantula is eating and moving normally, and whether the enclosure conditions match the species. That information helps your vet decide what care makes sense.

The most common cause is husbandry mismatch. Tarantulas kept too dry may become dehydrated and have trouble molting. Enclosures that stay too wet or poorly ventilated can encourage mold and other contamination. Species that need more humidity may struggle if the enclosure is overly dry, while arid species may do poorly in damp setups.

Stress and trauma are also major causes. Repeated handling can lead to hair flicking and bald abdominal patches. Falls are especially dangerous for terrestrial tarantulas because even a short drop can rupture the abdomen or crack the exoskeleton. Feeder insects left in the enclosure can bite a tarantula during premolt or after a shed, when the new cuticle is still soft.

Another important cause is dysecdysis, or an abnormal molt. A tarantula may get stuck in old exoskeleton, emerge with twisted legs, or show retained pieces of shed on the body. Dehydration, poor environmental conditions, weakness, and prior injury can all contribute.

Less commonly, abnormalities may be linked to fungal growth, mites or other parasite-related problems, mouthpart contamination, or abnormal healing after an old wound. Because these problems can overlap, your vet will usually look at the whole picture: species, enclosure, humidity, ventilation, molt history, feeding, and recent stressors.

Diagnosis starts with a careful history and husbandry review. Your vet will want to know the species, age if known, enclosure size, substrate type, humidity and temperature range, recent molts, feeding schedule, and whether there has been handling, a fall, or feeder insects left in the habitat. Clear photos from when the problem first appeared can be very helpful.

Your vet may first observe your tarantula inside the container to reduce stress and lower the risk of injury. In many invertebrates, behavior and posture provide important clues. A rounded abdomen, normal stance, and coordinated movement suggest a different level of concern than a death curl, collapse, or inability to right itself.

If needed, your vet may perform a gentle physical exam and assess whether the lesion looks like a bald spot, retained shed, trauma, contamination, or a true wound. In select cases, sedation or anesthesia may be used for wound care. Advanced testing is limited compared with dogs and cats, but your vet may still recommend lesion sampling, microscopy, or referral to an exotics clinician when the cause is unclear.

For pet parents, the most useful preparation is practical: bring the tarantula in a secure ventilated container, include the most recent exuvia if available, and write down the enclosure conditions as accurately as you can. That often shortens the path to an answer.

Prevention starts with species-appropriate husbandry. Match humidity, ventilation, substrate depth, and enclosure style to whether your tarantula is terrestrial, arboreal, or burrowing. Keep a clean water source available, avoid chronically wet substrate unless the species truly needs more moisture, and make sure the enclosure is secure and escape-proof.

Limit handling and fall risk. Many visible shell injuries happen after a drop, and terrestrial species are especially vulnerable because the abdomen can rupture. For ground-dwelling tarantulas, keep enclosure height low enough that a fall is less likely to be catastrophic. Use a catch-cup method instead of hand handling when you need to move your tarantula.

Protect your tarantula during premolt and post-molt periods. If your tarantula stops eating, darkens, or lays down a molt mat, remove uneaten prey and avoid disturbing it. Newly molted tarantulas have soft exoskeletons and are easy to injure. Wait until the fangs harden before feeding again.

Finally, watch for small changes early. A new bald patch, a dented abdomen, or a suspicious fuzzy spot is easier to address when your tarantula is still active and stable. Good records, good photos, and a relationship with an exotics-savvy vet can make a big difference.