REMINDER: The Enterprise in “Star Trek: The Next Generation” had a deck called Cetacean Ops, where dolphins and whales were crew mates who helped with navigation. It was referenced twice in the show, but never seen! (1/4) 
According to the Star Trek: The Next Generation Technical Manual (1991), “guidance and navigation research is conducted by twelve Bottlenose Dolphins (Tursiops truncatus) and Pacific Bottlenose Dolphins (Tursiops truncatus gilli), who are supervised by two Takaya’s Whales.” (2/4)
I like to believe this Starfleet-marine mammal partnership began with the events of “Star Trek IV: The Voyage Home,” when Spock and Kirk rescued whales aboard a Klingon Burd of Prey to save future Earth. (3/4)
Sadly, it was deemed prohibitively expensive for a meager TV budget to show onscreen, so our TNG cetacean crew remains forgotten lore. However, I suspect the character of Darwin in a future sci-fi series, “SeaQuest DSV” (which shares many Trek writers) was an homage... (4/4)
ADDENDUM: As a few astute Trekkies have pointed out, the in-canon references mentioned above are: a door in the TNG episode “We’ll Always Have Paris” labeled TURSIOPS CREW FACILITY; also, Geordi asks a visiting Ferengi if he’s seen the dolphins yet in “The Perfect Mate.” (5/4)
