Molting, scientifically known as ecdysis, is a fundamental biological process for tarantulas and all other arthropods. This mechanism involves shedding the old, restrictive outer covering, the exoskeleton, to facilitate growth and repair. Since the tarantula’s skeleton is a rigid external structure, it cannot expand like an internal skeleton. Molting is a necessary function that dictates the pace of a tarantula’s life, occurring cyclically throughout its lifespan and involving significant transformation and risk.
The Primary Reasons for Exoskeleton Shedding
The primary necessity driving molting is the tarantula’s need to grow, as the exoskeleton is an inflexible structure. A new, larger exoskeleton forms beneath the old one, and shedding allows the tarantula to expand in size. Younger tarantulas, often called slings, grow rapidly and may molt as frequently as once a month. As the tarantula matures, its growth rate slows, and adults may molt only once a year, serving more for maintenance than substantial size increases. Molting also provides the ability to repair damaged or lost body parts, such as re-growing a lost leg over a series of molts, and allows the tarantula to shed external parasites.
Recognizing the Pre-Molt Stage
The period leading up to the actual shedding, known as pre-molt, is indicated by distinct physical and behavioral changes. One reliable sign is a sudden and prolonged refusal to eat, which can last for days or weeks, as the tarantula instinctively fasts. A common physical indicator is a darkening of the abdomen, where the new, underlying exoskeleton becomes visible through the stretched old cuticle. The abdomen also often appears plump or swollen as the tarantula absorbs fluids to help separate the skin layers. Many tarantulas become lethargic and seek a secure, hidden location, sometimes creating a dense mat of silk on which to lie down for the process.
The Process and Recovery
When the tarantula is ready for the shedding itself (ecdysis), it typically flips onto its back. This position is normal and allows the tarantula to use gravity and hydraulic pressure to push free from the old skin. The old exoskeleton, called the exuvia, splits, and the tarantula slowly wriggles out, a process that can take fifteen minutes to over twenty-four hours depending on the animal’s size. Immediately after freeing itself, the new exoskeleton is soft, pale, and vulnerable, a state known as being teneral. The tarantula remains inactive while its new cuticle begins hardening (sclerotization), a recovery phase that lasts from several days to a few weeks, during which the soft fangs prevent eating or defense, requiring a stress-free environment until the new armor is fully hardened.