Replacements: Jason Cronin, Niall Horan, Leonard Mullane, Mike Cullane, Ciaran Cullane.
Replacements: Rory Harrison, Adam Clarkin, Brian Cawley, Luke McGrath, Niall Earls.
It is the first time since the All-Ireland League began back in 1991 that Shannon have lost their top flight status - they have been league champions on a record nine occasions.
Horan played 67 times for Ireland, including during the Grand Slam-winning campaign of 2009, and made a mammoth 225 appearances for his beloved Munster.
But this afternoon's crucial clash belonged to UCD who had by far the greater hunger and once they went in front with a James Thornton penalty after four minutes, the students were on their way.
They had the first of their five tries after 14 minutes when Shannon knocked on in attack, and dangerous winger Barry Daly raced clear for an opportunist score and Thornton converted.
By half-time UCD had the game as good as won when they led 16-0 with indiscipline proving costly for Shannon who conceded four chances to Thornton and replacement Niall Earls, three of which they converted between them.
Shannon were expected to mount some sort of a challenge in the second half but within five minutes Daly sprinted over from 70 metres out for a classy second try which Earls converted.
In the final quarter, Horan was replaced and UCD took complete control with intercept tries by busy number 8 Danny Kenny and prop James Tracy which Earls added the extras to.
The icing on the cake for Bobby Byrne's youngsters was an unconverted effort in the final minutes by inside centre Stephen Murphy, who followed up on his own grubber kick to touch down.
It was a great day for UCD, who finished behind champions Ballynahinch in Division 1B, but for Shannon it was one of the most disappointing occasions in the Limerick club's proud history.
Referee: Alain Rolland (IRFU)