Tarantulas grow by shedding their rigid outer layer, the exoskeleton, in a process called molting or ecdysis. This allows them to increase in size and regenerate lost or damaged limbs. Molting is a fundamental part of their life cycle, essential for their development.
The Molting Process
The molting process begins with a pre-molt phase, well before the actual shedding. During this period, a tarantula’s behavior and appearance change. They become less active and may stop eating, sometimes for weeks or months in adult specimens.
Physical indicators emerge, such as a darkening abdomen, especially noticeable in species with a bald spot, as new hairs form beneath the old exoskeleton. Some tarantulas, particularly New World species, spin a dense “molt mat” of silk for shedding. This mat often incorporates urticating hairs for protection during their vulnerable state.
When ready, the tarantula usually flips onto its back, though some may molt on their side or upright. This position is normal and not a sign of distress. The old exoskeleton then splits, typically along the carapace and abdomen, allowing the tarantula to slowly push its new, soft body out. They shed the outer linings of their fangs and eye coverings during this extraction.
Duration of Molting
The molting process duration varies considerably, influenced by the tarantula’s size, age, species, and environmental conditions. The pre-molt phase can last from a few weeks to several months, with adult tarantulas sometimes refusing food for up to three months.
The actual shedding of the exoskeleton is a shorter event, ranging from 15 minutes for spiderlings to 12-24 hours for larger adult tarantulas. For very large or older specimens, this active shedding can extend beyond a day.
Following shedding, the tarantula’s new exoskeleton is soft and pliable, requiring a hardening period. This post-molt hardening can take several days to two weeks, during which the tarantula remains vulnerable.
Molting frequency also depends on these factors. Young tarantulas, also known as spiderlings, molt more often, sometimes monthly or every few weeks, due to their rapid growth. As they mature, frequency decreases, with adult tarantulas molting once or twice a year or less frequently. Male tarantulas rarely molt again once sexually mature.
Post-Molting Care
After molting, a tarantula enters a particularly vulnerable period. The new exoskeleton is soft and susceptible to damage, so provide a calm and undisturbed environment. Avoid handling the tarantula or making sudden movements near its enclosure.
Ensuring access to fresh water is important, as hydration plays a role in the hardening process and recovery. Feeding should be avoided until the new exoskeleton, especially the fangs, has fully hardened. Soft fangs cannot effectively capture prey, and live prey introduced too early could injure the tarantula.
For spiderlings, their new exoskeleton may harden enough for feeding within two days. Larger adults may require one to four weeks before it is safe to offer food. Removing any uneaten prey items from the enclosure is important to prevent harm to the recovering tarantula.
Recognizing Molting Complications
While molting is a natural process, complications can arise. A common issue is a “stuck molt,” or dysecdysis, where the tarantula struggles to fully shed its old exoskeleton. This can occur if environmental conditions, particularly humidity, are too low, preventing easy detachment.
Signs of a problem include a molt taking significantly longer than typical for the tarantula’s size and age, or if shedding appears asymmetrical. If limbs, pedipalps, or chelicerae become trapped, it can lead to deformities or an inability to eat.
Intervention is generally discouraged, as attempting to assist can cause more harm due to the tarantula’s fragility. Maintaining proper hydration and humidity in the enclosure prior to and during the molt is the most effective preventative measure. If a tarantula struggles, a light misting with tepid water might help soften the remaining exoskeleton, but physical manipulation can cause serious injury.