The Bionicle universe has an…interesting fauna. Even though the Toa, Matoran, and Rahi are all biomechanical, many of them share qualities with creatures from our world. The Nui-Jaga look a lot like scorpions, the Muaka are similar to big cats, and Ruki fish are…well, fish.
Even though the MU doesn’t have scientific classifications for the Rahi (at least, that we know of), I felt kind of curious as to just how many species there were. So I went onto this Biosector01 page and checked it out.
If I counted correctly, then there are 159 species of Rahi listed on this page. Granted, there are some different breeds or sub-species (like with the Visorak), but it appears that they’re still considered the same genetic species. But that’s just with nonsentient beings. There’s also this page:
There aren’t as many sapient beings as there are Rahi, but there’s still a good amount. The Makuta, the Vortixx, the Skakdi, the Zyglak, Frostelus, and the Bahrag all add up to six, and given that Matoran can become Toa, and Toa can become Turaga, I’d say they all collectively count as one species. So that’s seven species, plus the aforementioned 159 species of Rahi. Oh, but it gets better.
This article compiles a list of 26 unnamed species, and it mentions that there are even more unnamed species that form the Dark Hunters and the Order Of Mata Nui. Not to mention, there could be even more species of Rahi that we don’t know about.
Just for comparison, there’s some 8.7 million organisms on Earth. But still. Mata Nui and the Great Beings must’ve had their work cut out for them, creating all those species.