Waikiru were a species of Rahi.
The Waikiru are one of the many species to be created by the Brotherhood of Makuta using viruses and Energized Protodermis to populate the Matoran Universe.
The Waikiru lived in the seas near the surrounding area of Ga-Metru in Metru Nui. After the Great Cataclysm, the Waikiru were forced to migrate to the island of Mata Nui. The Waikiru had a clolony in the shores of Ga-Wahi.
Mata Nui's population of Waikiru was forced to migrate back to Metru Nui after the Toa Nuva unleashed the Bohrok Swarms on the island. The Waikiru succesfully arrived to the Matoran Universe, where they resided for some time.
After Teridax was killed by a fragment of Aqua Magna, the Waikiru and the other Rahi will have to join the mass exodus to Spherus Magna to escape the Matoran Universe before it finally breaks down in order to survive.
The Waikiru were a species of clumsy Walruss-like mammals that inhabited the island of Mata Nui. They had next to no storyline significance.