Excellent immunitary defenses
|Out of Stargate universe information|
The Goa'uld are a race of sentient parasitic beings with a snake-like shape originated from P3X-888.
If we look to their original shape, the Goa'uld look like small snakes and can only live in a tempered and damp environment, and with the presence of a constant feeble electrical charge. Those conditions exist on P3X-888, their planet of origin. To move outside their lake, they need a host whom they take possession by piercing the neck and wrapping around the spine, then they extend filaments that take control of the brain. The first hosts have been Unas, inhabitant of P3X-888 like them, then they took humans, both of them presenting ideal surviving conditions for the symbiote (SG1: "Children of the Gods", "Bloodlines", "Bane", "The First Ones", "The Enemy Within", "Thor's Hammer").
According to the P3X-888's archeleogical diggings, it appears that the Goa'uld have evolved as predators in the prehistorical oceans of the planet for millions of years before taking hosts. On the fossilized rests found on the planet, there is no trace of naquadah in their system, indicating that this genetic mark appeared much later during their evolution (SG1: "The First Ones").