Molting/Ecdysis

Ecdysis, also called molting, is the act of shedding the exoskeletons in arthropods, tarantulas included. In order for them to grow they must molt, it is a complex process involving hormones, proteins, and enzymes.

Some reptiles, such as snakes, shed all their skin at once leaving behind an opaque shedding. The molting of an arthropod can be more life-altering. At certain stages of life an arthropod may undergo a biological process and they physically change, this is called metamorphosis. Many arthropods acquire a new form at different developmental stages, such as larva to pupa then to adult becoming sexually mature (i.e. butterfly); these points of developmental changes are called instars or stadium. Depending upon the species, the physical changes vary greatly.

Tarantulas do not acquire a new form after casting off the chorion, the outer shell of the embryo (spider egg) as some other arthropods. After the first two or three instars, it is difficult to determine the tarantula’s age.

Pre-molt, tarantula will refuse food. Age drastically influences the time-span of the fasting period. Adults may not eat for several weeks or months before molting. Some species will spin webbing to create a molting sanctuary, varying by species. They may entomb themselves, place a layer of webbing on the ground to rest on, or do little at all and seek out a natural refuge. Darkening in appearance and lethargic behavior occurs, which is challenging to observe.

During ecdysis, tarantulas are very vulnerable. Often they will lie upside down and slowly move to a clenched state. The pumping of inner fluid causes the exoskeleton to split and proteins form a new cuticle. Slowly, the newly formed exoskeleton emerges from its epidermis husk. The time it takes to complete the molting process varies, from minutes to hours. It is imperative they are not disturbed during this period.

Post-molt, the tarantulas’ fangs appear milky and they will remain motionless as the exoskeleton hardens. Juveniles may not resume feeding for a few days and adults for two weeks.