Why is spider digestion called external?

Spiders are the only animals that digest their food outside of their bodies. After capturing their prey, spiders send digestive enzymes from the intestinal tract to the victim. Enzymes destroy her body tissues, and after a few seconds, the spider sucks in the congested liquid tissue. By repeating this process many times, the spiders digest the entire animal. Spiders have a sucking stomach, which is the main pump for drawing food into the body. Almost all spiders have venom glands. Spider venoms, which are composed of several different proteins, act on various substances in the insect’s nervous systems.