How Do Spiders Change Their Skin?

In order to grow, spiders undergo several moults during their lifetime. Each time they molt they break down the old exoskeleton and grow a new one. The process is called ecdysis.

The ecdysis is triggered by hormones in the spider’s body. It is a complex energy-demanding process that is not easy to watch. It can lead to mutilation, suffocation and death for spiders that aren’t able to complete the molting process.

During ecdysis, the spider’s internal organs, including its heart, expand. They do this by pumping their blood, which in turn fills the cephalothorax. After this, the abdomen splits, leaving the legs free to move.

The spider’s exoskeleton is a hard layer of skin that provides protection. It is made of protein molecules, long-chain polysaccharide, and chitin. It can be seen from outside the spider’s body. The exoskeleton is flexible for movement, but isn’t expandable like human skin.

The exoskeleton is divided into two layers: the outer layer is called the exocuticle. The inner layer is called the endocuticle. The new exoskeleton grows underneath the exocuticle. The new exocuticle is smaller than the old one, allowing the spider to expand.

When the spider is ready to molt, it will wriggle out of the exoskeleton. It may appear wrinkled or have bald spots. Depending on the size of the spider, this process can take minutes to days. After molting, the spider will usually stay on its back, resting.

The exocuticle is then digested by digestive enzymes. Inactive enzymes prevent the digestion of the new procuticle.