As we in America saw earlier tonight on 'Doctor Who', Starship UK was strapped to the back of a giant starwhale. According to Queen Elizabeth the Tenth ("Liz 10"), there used to be millions of these gentle creatures in space, guiding lost space travelers.
There may still be others, somewhere off in the Gamma quadrant, perhaps, but as far as the Space Brits knew, this starwhale was the last of its kind.
I think it's highly likely, and Toobworld Central is going to proclaim it so, that the space whale which found its way through the Rift to end up in Cardiff (as seen in the 'Torchwood' episode "Meat") was of the same general species as the starwhale seen in "The Beast Below".
And sadly, its fate could splain away what happened to all of the other starwhales across the universe.... BCnU!