"One time in med school, I made the mistake of confiding to my partner in biology class that it had caused my all-time worst nightmares. He actually planted a live snake inside a cadaver I was working on."
Dr. Jennifer Keller[src]

Snakes are elongate, legless, carnivorous reptiles. Dr. Jennifer Keller once had a live snake implanted in a cadaver she was working on at med school by a fellow student. (SGA: "Doppelganger")

While under the affect of an Alien tick Airman Dunning believed there was a snake under the skin of his arm, which he tried to claw at and ripped the skin from his arm. (SGU: "Pain")

Colonel Jack O'Neill often refers to Goa'uld as 'snakes' or 'snakehead'.