I've been off work this week which is giving me a chance to go through many of my unprocessed images from the last couple of years.
In July last year I witnessed and photographed a Giant House Spider (Tegenaria gigantea / duellica) sloughing (shedding its skin). This entire process took two hours to complete and was fascinating to watch:
The cephalothorax splits across the back and the spider begins the arduous task of forcing itself out of the old skin. This is done in several stages with the spider taking time to rest regularly while it regains its strength before continuing. The only part of the spider that is attached to the old skin is at the base of the abdomen.
Eventually the spider breaks free and lays motionless for several minutes, completely exhausted. In this exhausted state the spider is highly vulnerable.
When the spider has regained enough energy it prepares itself to stand on its new legs. Spiders are exo-skeletal so at this stage the limbs are still very soft and flexible and are unable to support the weight of the spider.
The spider finally manages to get itself upright. It quickly stretches out its new legs. Here it must remain and wait patiently while the new skin hardens sufficiently to fully support the spider. The soft new skin is quite translucent and the spider looks very different than before.
After waiting for over an hour the spider's skin is now able to provide the skeletal support enabling the spider to walk once again. The spider is still exhausted and the new skin has still not fully hardened so once able to walk the spider abandons the old slough and heads off seeking cover where it can hide until fully recovered.
The old abandoned slough is 20% smaller than the newly emerged spider.
Larger images are posted on my website here: http://www.jasonsteelwildlifephotography.yolasite.com/spiders.php