Hello:
This is my interpretation of Species 8472 based on the few episodes they appeared on and extrapolating from "Star Trek: Armada 2":
After the truce between Starfleet and Species 8472 there is now so much new information that became freely available about this species. Species 8472 is actually two types of organisms that work as one in a very advanced type of symbiosis: The Bioships that can freely navigate Fluidic Space and the tripedal "Pilots" that handle every system/organ from inside. There is no information available as to when or why this happened, but the bioship and it's pilot minds are separated but act as one. The number of "pilots" a bioship needs depend on the type.
The way Species 8472 organize can only be compared and be analogous to termite colonies, a species from Earth that mastered agriculture dozens of millions of years ago. And, in a similar way, the bioships can be separated between a Warrior Caste and a Worker Caste.
Each caste of bioships have members of different sizes and even specialization, and they fill distinctive roles: The workers gather and distribute resources, help mantain other bioships and can even become supplementary reproductives, but they are unarmed. While the warriors have no qualms in giving their lives for the protection of fellow colony siblings and their parents, members of the warrior caste are peaceful when things are quiet, but when a threat appears they'll show unparallel ferocity.
As mentioned before, Species 8472 organize in colonies that settle in different regions. For a new colony to start, a Royal Warrior and a Royal Worker are needed to meet and they become partners for life, they represent the largest bioships from each caste and are genetically designed to be the main reproductives for new colonies.
Here are the preview renders of the two Species 8472 Royals:
1) The Royal Worker, otherwise known as the Mothership, has the role of creating the larvae for every bioship and biostations in the new colony. As a member of the Worker Caste, it is unarmed and needs to be defended. The Mothership has a small community of "pilots" and can also incubate new ones in preparation to join them to every new bioship as they grow.
2) The Royal Warrior, otherwise known as the Fathership, has the role of defending it's partner and the fledgeling colony. It is armed with three starbase-grade pulse weapons and a heavy beam weapon. The Fathership also has a small community of "pilots".
The idea of the Royals having communities of "pilots" help the species with genetic variety, as the newly grown bioships and their "pilots" are, by old means, the children of their Royal parents.
The Royal Warrior/Fathership was made by me based on a designed by
@Epytron_Omega .