Chelicerae - Spider Jaws

This is a close-up view, at very high magnification, of various chelicerae - that is, the jaws of a spider.  How do they work?  Rod Crawford, a spider expert at the Burke Museum of Natural History and Culture, University of Washington, answers that question:

Spiders are not miniature vampires; all species, as far as we know, digest some solid parts of their prey. What makes it especially interesting is that the digestion process begins outside the spider, where anyone who wants to look can see how it works.

Put a medium-sized insect in the web of a large orbweaving spider in the garden. You will see the spider bite the prey, wrap it in silk, wait for it to die, then begin to eat. As a first step in eating, the spider will literally vomit digestive fluid over the prey. Then the prey is chewed with the "jaws" (chelicerae), and the fluid is sucked back into the mouth together with some liquefied "meat" from the prey. The spider repeats this process as often as necessary to digest, and ingest, all but the inedible hard parts. What is discarded afterwards is a small ball of residue.

Click on the image to greatly enlarge the view.