Monday, April 16, 2012
Animal caretakers Adrian Eng and Cari Garand had the good luck to be present for an unexpected and fascinating view of a spider shedding her skin. But if it took luck to be present, it took patience, understanding and care to observe this phenomenon from beginning to end without disturbing the spider.
This week we got a chance to witness one of our garden orb weavers shed its carapace.
When we spotted our garden orb weaver shedding she hung from her own spun web with all eight of her legs gripping on silk. The top cap of her thorax had peeled back and her abdomen began to pull away from her old skin. She retreated from her exoskeleton by pulling downwards while her old skin remained hanging from the web. She looked very uncomfortable and as she pulled away and her legs seem twitch as she struggled to escape. As soon as she pulled completely away from her old skin she righted herself up. After shedding, her skin was soft and weak. Her legs almost dangled like an octopus out of water. As more time went by I notice her skin darkening and begin to harden. Within the day she was back to looking normal.
Molting is a dangerous time, but our spider needed to do it in order to grow. Spiders and other arthropods do not have an internal skeleton like mammals, fishes, reptiles and birds. Instead, spiders have an outside covering (exoskeleton) made up of layers of carbohydrates and proteins. Because their exoskeleton is hard and durable, it does not grow. Spiders need to go through a series of molts until they are adults. During their molt period they are susceptible to attack and need time to rest and grow. If they do not escape from their old exoskeleton in time they risk being trapped and subsequently die.
-Cari Garand, photos
Congratulations to our spider on her successful shed, and to our staff members for noticing and documenting this amazing transition.