Theta Tau V was an M-Class planet considered for colonization by the Federation in the 2260s. The planet was visited by a landing party from the USS Enterprise consisting of James T. Kirk, Spock, Leonard McCoy, and Hikaru Sulu. The team discovered plant and animal life which exhibited hyperaccelerated metabolism, as well as extreme and quickly changing weather patterns. Kirk was injured during the mission, but recovered with the care of Dr. McCoy.
Following the Enterprise's visit, Theta Tau V was presumably discounted as a colony site. (TOS short story: "The Quick and the Dead")