Large space-dwelling creatures from Tychus-B, one of which the Lutani fitted with a neural device to use as a weapon of war while the USS Enterprise escorted it.
The Jikaru appear in the Strange New Worlds episode What Is Starfleet?, which is presented as a documentary filmed aboard the USS Enterprise by Beto Ortegas. The ship is ordered to move a Jikaru, described to the crew as livestock, from Tychus-B to the war-torn world Lutani VII.
The creature can release intense bursts of radiation, and it cripples a scout ship that attacks the convoy. The crew learn that the Lutani have conditioned it with a neural implant and mean to turn it on their enemies, the Kasar. Uhura makes contact with it and finds a thinking being in great pain.
The Jikaru wishes to end its suffering by flying into the system's sun, and asks only that its unaltered young be kept safe. Pike lets it go and has Starfleet place Tychus-B under quarantine.