The Goa’uld themselves are small snake-like Symbiotes that require a host body. Once they burrow into a body, which can be accomplished by piercing the skin in the neck, the parasite begins to wrap itself around the spine. The symbiote then weaves itself around the nervous system where thin filaments are extended that go up into the brain itself.
Once the Goa’uld has taken control of the host body and has become one with it, it possesses the capacity to exert a remarkable level of control over it. This allows them the capacity to kill the host at will if need be or if they are threatened by others. Standard surgical techniques have proven to be ineffective in removing the symbiote. Even advanced Humans can be susceptible to this as the symbiote can release a deadly poison that can kill the host upon removal. However, the advanced techniques of the Tok’ra allow them to safely remove a symbiote without causing any permanent physical damage to the host. However it is never certain that the symbiont will not release a poison even if the Tok’ra try to remove it.
Infant Goa’uld that have not reached maturity are not capable of fully taking over a host and only retain control of them for short periods of time which are experienced as black outs by the host. This results in a struggle being fought over the host body between the symbiote and the host itself. In its young state, a symbiote is capable of shedding a dead husk of skin that resembles its body and can make surgeons believe they removed the Goa’uld.
A special class of Goa’uld are the Queens which are responsible for producing new young larval Goa’uld for implantation into Jaffa. When encountering a new tribe of Humans or a different race, the Queen requires to first sample the DNA, or “code of life” as the Goa’uld refer to it, from the species intended to be a host. This is to ensure that there is no rejection during the process between host and larva.
One of the unique factors of the Goa’uld race includes their genetic memory which provides each newborn symbiote the collective knowledge of all the Goa’uld that came before it. Another element included within their body’s ia Naquadah which serves as a key to activating their technology and even allows them to sense the Naquadah present within a Stargate. This does not appear to be a natural aspect of their biology, however, as the early Goa’uld lacked this element within their blood chemistry.
Within a host, a Goa’uld parasite has complete control, and the degree of control to exert at any given moment is also up to the parasite. Typically entering in through the neck and more seldom through the throat, the Goa’uld will attach itself to the spinal cord which allows access to the brain, leaving an entry mark. When within a host, the Goa’uld gives perfect health, increased strength, and increased intelligence. When in control of the body, the symbiote is capable of making the hosts eyes glow, and also speak in a deep, booming voice. The voice, however, is unnecessary. It may be used to differentiate between parasite and host, as the Tok’ra do, or simply be used to intimidate slaves and opponents.
Being taken as a host by a Goa’uld is often considered a terrible fate for the host, as they are suppressed and forced to witness countless horrors. The Goa’uld maintain that the host essentially dies when the Goa’uld takes control, but this has been proven false on numerous occasions. However, a System Lord’s lo’taur often considers being taken as a host a “great honor” (they are also around just in case something happens to the host), and indeed even non-Tok’ra Goa’uld and their hosts sometimes coexist willingly (for example Kianna Cyr and possibly Hathor). Certain strong-willed hosts are capable of fighting the control of younger symbiotes that have infested them although only to a marginal extent, such as suppressing a hand movement for a few seconds.
The Goa’uld are capable of infesting a wide variety of hosts, from Humans to Unas (which were the Goa’uld’s first hosts, because they shared their homeworld with them). They can also take Asgard bodies as hosts for a short period of time, though the Asgard’s genetic makeup eventually rejects the symbiote causing the host’s body to wither and die. Two species which cannot be taken as hosts are the Ilempiri and Jaffa.
A child of two Goa’uld hosts is called Harcesis and has all the genetic memory of the Goa’uld.
One of the most likely threats a Goa’uld lord can face is being challenged by their children.
The final wish a Goa’uld can give their First Prime was the task of avenging their death if they were betrayed or killed by a rival.
Minor Goa’uld are often forced to serve the more powerful as Underlords and can consist of former warlords that were defeated. While they can serve as lieutenants and commander for the lord in question, there was the danger of the Underlord plotting to overthrow their master. This threat is even greater when one considers, if successful the usurper would gain all the holdings of their master.
The highest authority among the Goa’uld race included the ranks of the System Lords who fielded vast armies under their command as well as warred with one another for dominance. Whenever a System Lord or Minor Goa’uld was vanquished, it was common practice that their domain was absorbed into the victor’s ranks. This usually was more than enough incentive for a Goa’uld to go to war with his neighbor and win at all cost.
They make use of personal servants who are normal humans known as Lo’taur that served their every needs. On some occasions, the Lo’taur was used to serve as a spy and gain vital information from the other Lo’taur. An additional benefit of having a Lo’taur is that the Lo’taur can be used as an emergency host. Some Lo’taurs even felt honored by this possibility.
The Goa’uld are known to speak both Goa’uld dialects and simple English.