All flood start off as an infection form. They can be identified their barbed tentacles and their bloated gas sack. They are weak and fragile on their own but with enough of them together they can overwhelm a host begin taking over the host's body. The barbs on the end of the Infection form's tentacles stick into the host and release spores that bein to mutate the host and the tentacle's become  the new nervous system. The host then mutates into one of 3 forms. The Warrior/worker Form, the Carrier form, and the Brain Form.

 

When the host that the infection form infected is deemed suitable the Infection form will then begin to transform the host a worker/warrior class. This class is exactly what it says, its job is to repair vehicles and defend against attackers and attacks others for infection suitible species for infection purposes. The worker/warrior class usually have a tentacle appendage sprouting from one the their arms, usually breaking the bones to move them out of the way. These flood seem to retain mefmory as they use the weapons they used while uninfected.

 

The carrier form is formed when a WOrker/warrior class has taken too much damge, when the worker/warror runs out of calcium deposits, or dosent have sufficient mass for Combat. The carrier form is what grows the new infection forms. It can be spotted its hideously deformed and bloated sac on the entire top half of the body. It has tentacles from its previous incarnation but no longer uses them. When the Carrier form is near a suitable host or has taken enough damage it starts of a biochemical reaction that causes the bloated sac on top to burst releasing all the stored flood infection forms thus starting the whole life cycle over again for the flood.

 

When the Infection form flood determines that its host has sufficient memories it will convert the host into a brain flood. The infection takes more of the memories of the host when in this form as to supply orders to the lesser beings on what to do. The victims of this form tend to be higher ranking officials like captains.

 

Little is kown about this flood form. It seems to command the flood and has the abiltiy to use the Instalation's Teleportation Grid. It also seems to display more intelligence than the other forms of the flood.