G. cancriformis is a predatory organism, feeding on other insects like beetles, fruit flies, moths, and whiteflies. Females use their complex web to capture and trap their prey. She sits in the middle of the web facedown, and as the prey approaches the web, the female quickly moves toward the victim and wraps it in silk. She then bites it, emitting poison to paralyze it, and eats the insides of the organism.

G. cancriformis lacks mouth parts to eat the solid parts of its prey, so it has developed mechanisms to ingest the liquids inside. The poison serves as a dual purpose, digesting the insides while paralyzing the prey. This is helpful so the spider can suck out the partially digested insides as its meal.

 The Spiny Backed Orb Weaver has a complete digestive system, containing a mouth and anus, along with an open circulatory system for nutrition transfer.