Arex Lieutenant Arex was a male Edosian Starfleet officer who lived during the mid - 23rd century . He served in the command division aboard the under Captain James T . Kirk , during a historic five - year mission that starship undertook . From 2269 to 2270 , Arex served as one of the ship ' s primary navigator s . While under the influence of Harry Mudd ' s love potion , Arex sat at the navigator ' s station playing a lute , instead of attending to his duties . ( ) Upon the " Enterprise " s encounter with spiroid epsilon wave s , he was momentarily blinded , but suffered no permanent vision damage . Later , he reported that he could no longer perform visual sweeps , as his eye s were too small for the opticals . ( ) He was given the conn following Lieutenant Nyota Uhura ' s disappearance of the Shore Leave Planet . ( ) When Commander Spock was incapacitated by choriocytosis , Arex assumed his duties at the " Enterprise " s science station in 2270 . ( ) While the rest of the command crew was having a staff lunch , Arex was temporarily in command of the " Enterprise " . He later took his lunch break with M ' Ress , asking Mister Scott if he wanted to join them . Shortly after , Scott blamed them for the malfunctioning food dispenser s and threatened to report them to the captain , but Arex maintained their innocence . ( ) When the " Enterprise " entered a negative universe in 2270 , Arex began to grow younger , eventually becoming a child . His condition was reversed by Dr . McCoy using the ship ' s transporter . ( ) Appendices . Background information . Including Arex in " " accomplished two goals : it provided variety with yet another " alien " crew - member that an animated series could afford , and it replaced Pavel Chekov without employing an additional actor . Although Arex is clearly shown to be a navigator , the final draft script of refers to him as " the alternate helmsman " . In the same script , Arex is also described as " male , but his voice has a soft , musical tone . . . on the tenor side . " The was provided by James Doohan . According to StarTrek . com , Arex was Pavel Chekov ' s navigation instructor at Starfleet Academy . This information comes from a 1973 newsletter by Gene Roddenberry and D . C . Fontana , which described the " Animated Series " in general , and gave detailed bios of Arex and M ' Ress . It also states Arex is a veteran and known as the best navigator in Starfleet . He began his career as a technician serving on merchant vessels , and not going through Starfleet Academy , he became an officer via " field commission " . " " While Arex appears to be a quiet , efficient , junior officer , Captain Kirk knows the Lieutenant is entitled to wear three decorations for bravery and has a Starfleet Citation for Conspicuous Valor . Arex himself would never mention them . " " Apocrypha . Arex appeared briefly in the novels " The Galactic Whirlpool " , " Time for Yesterday " , " The Fire and the Rose " and the graphic novel version of " The Ashes of Eden " . He made several appearances in the first volume of DC ' s " Star Trek " comics , which were set after . He has become a minor character in the " " series , where he serves as a security officer on the " Trident " under Captain Shelby . In these novels , his full name is given as " Arex Na Eth " . Arex ' homeworld Edos was first mentioned in Lincoln Enterprises publicity material in 1974 . Arex is referred to as an " Edoan " in Alan Dean Foster ' s " Star Trek Log " series of novelizations . According to the " Star Trek : New Frontier " novels , Arex is described as a Triexian . " The Latter Fire " also corroborates this . Arex ' s biography on StarTrek . com describes him as an only child , but the novel " Cold Wars " describes him as part of a very large family with eleven brothers and thirteen sisters . In IDW Publishing ' s comics , Arex is telepathic .