Four different species of Rahi. Clockwise from top left: Tarakava, Kikanalo, Visorak, and Kane-Ra.
Rahi are biomechanical creatures that served as the fauna of the Matoran Universe.
Behavior-wise, Rahi heavily resemble the animals of Earth and the indigenous fauna of other worlds in that they have limited intelligence and their primary concern is survival. However, some Rahi have demonstrated a much higher form of sentience than most: at least two species, the Tahtorak and the Zivon, are capable of intelligent thinking and conversing in Matoran speech. Though some species of Rahi were domesticated by the Matoran and trained to assist them in their daily tasks by pulling carts or serving as a form of transport, many were deemed too aggressive or dangerous to domesticate and left to roam in the wild.
Rahi sustain themselves by absorbing energy from organic matter through physical contact. Due to their biomechanical nature, Rahi are not capable of biological reproduction: only the Makuta and the Great Beings are known to be able to create new, properly functioning Rahi.
For the most part, the Makuta created Rahi like they would create machines or any other kind of complex technological device. First, a Makuta assigned to Rahi creation would come up with an idea for a Rahi, which would then be developed into a plan that outlined the Rahi's features, characteristics, and intended role in the Matoran Universe's ecosystem. Then, the Makuta would mold batches of raw protodermis into organic and inorganic components that would together make up the entirety of the Rahi's body, unless the creator wished to add additional materials to the design such as protosteel armor or weapons. If the Rahi had any special features, like motorized treads or defensive powers, these features would often be tested in a lab environment to ensure that they functioned correctly before the Rahi was put into production. The final stage of development entailed the Makuta "programming" the Rahi by selecting behavioural characteristics from Makuta viruses and transferring them into the Rahi's neural center, or brain, in vats of liquid protodermis before activation.
The first Rahi were created by the Great Beings on Spherus Magna during the construction of Mata Nui. It was unclear what purpose the Rahi were intended to serve inside the Matoran Universe, but the Great Beings considered them important enough to populate it with various species of Rahi shortly before Mata Nui was first activated. From then onwards, the responsibility to create Rahi fell to the Brotherhood of Makuta. Almost all Makuta went on to create at least one species of Rahi at some point in their lives.
In 625 CMT, Makuta Starok created a splinter faction of the Brotherhood of Makuta that came to be known as "The Reformed Second Brotherhood of Makuta". One of the main goals of this organization was to populate alien worlds with Rahi and Matoran, which they did by launching Rahi at planets with warp-pods, which proved to be an extremely efficient method of population. Eventually, the TrSBoM turned their efforts to creating new species of Rahi, but it is unknown how successful this venture was.
When the main Brotherhood of Makuta began to stray from their original purpose and develop into a militaristic organization, higher-ranked Makuta neglected their duties to create Rahi and instead turned their attention to furthering the Brotherhood's (or their own) goals of conquest. To ensure that Rahi would continue to be created, the organization's leaders forced lower-ranked Makuta, like Ynot, to develop Rahi full-time while the higher-ranked Makuta left to pursue more exciting goals.
Throughout the entirety of Teridax's reign as the Grand Master of the Brotherhood of Makuta, Ynot's only task was to create new Rahi. On at least one occasion, Ynot altered the dietary requirements of one of his Rahi so that it could eat something that was more abundant in its habitat. In 50,080 CMT, Ynot was working on a Rahi when Sasuken handed him a Tablet of Relief, explaining that they had been relieved of their present duties because Teridax required them to chart the newly-discovered island of Shinobi-Nui.
Much of the Matoran Universe's Rahi were either killed or starved to death when Blackout used persuasion particles to convince the Matoran to dismantle the Matoran Universe and rebuild it into Darkmount. However, some Rahi were likely saved by Artakha or other beings who evacuated the Matoran Universe before its destruction, such as the Nynrah Ghosts. The land-dwelling Rahi species, who had been stripped of their habitat by Blackout, were saved from extinction by the Great Beings, who used the Brotherhood of Makuta's Rahi design documents to create more of them. Some of these Rahi were trained for combat and added to the Great Beings' armies: a large chunk of Serecio's army consisted of, amongst other Rahi, space-adapted Blade Dragons for space and aerial assaults, and thousands of rampaging Nui-Kiru.
Known Rahi species
|Blade Dragons||Blackout||Alive; populous in the Great Beings' armies|
|Frost Vultures||Blackout||Alive; populous in the Great Beings' armies|
|Gadunka||Unknown||Alive; populous in the oceans of Aqua Magna|
|Kardas Dragons||Unknown||Alive; status of original specimen unknown; design reproduced by the Makuta Anima|
|Más Pequeños||Unknown||Alive; design reproduced by the Makuta Anima|
|Nui-Kiru||Kakamu||Alive; populous in the Great Beings' armies|
|Rahi Nui||Unknown||Alive; populous on Shinobi-Nui|
|Tahtorak||Miserix||Alive; populous on Shinobi-Nui|
|Tarakava||Unknown||Alive; populous on Shinobi-Nui|
|Zahgargak||Unknown||Original specimen alive; design reproduced by the Makuta Anima|
|The Zivon||Unknown||Extinct; only known specimen deceased|
- In the Shattered Mirror Universe, several species of Rahi participated in the Battle of Destral: SM Trantoshen's forces included Visorak-Rahkshi hybrids, and SM Ynot's included the Zivon and at least one Tahtorak.
- The Reformed Second Brotherhood of Makuta (revision on 15:15, Dec 26, 2009): "The Reformed Second Brotherhood of Makuta is an organization mainly populated by Makuta devoted to populating uninhabited worlds with Rahi and members of the Matoran species. [...] It has advanced labs and warp-pods, Devices capable of firing Rahi to far-out planets at great speed allowing for quicker population. [...] Eventually, TrsBoM turned their objectives to creating new Rahi, and as such they began building bases to populate un-inhabited worlds."
- BZPB: Future #15175 (Jan 27, 2014)
- Tales of the Makuta Anima | Chapter 1
- Trantoshen (SMU) (revision on 18:28, Dec 11, 2011): "Despite SMT's armies of Bohrok and Visorak/Rahkshi hybrids, SMY still managed to break into the fortress and attack Trantoshen. SMT then ended up being dragged into the path of a raging Tahtorak. He used a Komau to force the Tahtorak to attack a Zivon, but was crushed in the process and recovered by Spiriah."