Tarantulas inspire fascination, especially regarding their growth process. Unlike mammals, these large arachnids grow by completely shedding their outer layer. This necessary and regular process, known as molting or ecdysis, leads many to wonder about the fate of the shed skin: does the tarantula consume its own molt?
The Biological Necessity of Molting
Tarantulas are arthropods, meaning they possess a rigid external skeleton, or exoskeleton, composed primarily of chitin and protein. This hard shell provides support and protection against injury and water loss, but it cannot expand as the spider grows. To increase in size, the tarantula must undergo ecdysis, a complex biological process that allows for a complete renewal of its outer structure.
The molting cycle begins with a pre-molt phase where the spider stops feeding, and a new, soft exoskeleton forms beneath the old one. During this time, the tarantula secretes enzymes that partially dissolve the inner layer of the old cuticle, separating the new skin from the old. When ready to shed, the tarantula typically flips onto its back, a position often mistaken for death, and pumps its internal fluid (hemolymph) to build pressure. This internal pressure causes the old exoskeleton to split, usually around the carapace and abdomen, allowing the tarantula to slowly pull itself free.
Shedding is a physically demanding event that can take several hours for an adult tarantula, and the new exoskeleton is completely soft and vulnerable immediately afterward. Molting is not solely for growth; it also provides the tarantula with a way to repair damage, such as regenerating a lost leg or replacing worn-out sensory hairs. The tarantula remains in a state of soft vulnerability while the new cuticle hardens, a process that can take a week or more depending on its size and species.
Do Tarantulas Consume Their Exoskeleton?
The definitive answer to whether tarantulas eat their molt is generally no, they do not consume the entire shed exoskeleton. This behavior is common in some other invertebrates, like insects and crustaceans, which may re-ingest their shed skin to reclaim minerals. However, tarantulas possess a different feeding method where they liquefy their prey internally with digestive juices before sucking up the nutrient-rich fluid, leaving behind the prey’s external casing.
The shed exoskeleton, or exuvia, is essentially a hollow shell of indigestible chitin and protein, holding very little nutritional value that the tarantula can easily process. Furthermore, the molt of New World tarantulas is covered in urticating (irritating) hairs that they likely avoid consuming. Any observed instances of a tarantula appearing to “eat” its molt are usually limited to the compression or manipulation of the material.
A tarantula may sometimes chew or compact the shed skin, particularly the softer parts like the abdomen or the area around the book lungs. This action is most often attributed to the spider attempting to extract any remaining moisture, or to simply move the large, obstructive object out of its immediate space. Reabsorbing any residual moisture from the exuvia can be a temporary source of hydration, especially for species that naturally inhabit drier environments.
Disposal and Post-Molt Behavior
Since the tarantula does not typically consume its molt, the exuvia usually remains in the enclosure until the spider or an outside source removes it. The shed skin often appears as a perfect, translucent replica of the spider, including the linings of the trachea, book lungs, and even the fangs. The tarantula’s immediate post-molt behavior involves a long period of rest while the new exoskeleton hardens and the fangs calcify, making it temporarily unable to eat.
Once recovered, the tarantula will actively manage the presence of the large, empty skin. They may push the exuvia away from their retreat, sometimes incorporating it into the webbing that lines their burrow or simply tossing it to the periphery of their habitat. For keepers, the intact exuvia is highly valuable because the sex of the tarantula can often be determined by examining the shed abdominal lining for the presence of spermathecae, reproductive organs found only in females. The post-molt period also involves the tarantula performing stretching motions to ensure the new exoskeleton dries and hardens in a properly extended shape.