Luis Bunuel and Salvador Dali were adamant that Un Chien Andalou contained no symbolism whatsoever. Their goal was to make a film full of imagery that could not be explained or rationalized. I like that, because it lets me form my own interpretations.
There is a shot in this film featuring ants pouring from a hole in a young man’s hand. At first, I didn’t quite know how to interpret this. Dali associated ants with death and decay, but beyond that I wasn’t sure what it might mean. A short while later, when the man tries to sexually assault a young woman, I immediately thought of the ants in his palm. I felt that the ants represented the ugliness and repulsiveness of his urge to put his hands on her against her will.
Another interesting sequence, probably my favorite in the film, was at the very end. A happy couple walks down the beach, smiling and clinging to each other. It appears to be the final shot. Then a title card appears with the words “In Spring”, followed by a shot of the couple, now dead, buried in the sand up to their chests. A couple of thoughts came to mind: first, the title card places this scene in springtime, so my immediate (and silly) thought was that the couple had been planted as flowers. Also, Dali was a bit obsessed with a painting by Jean-Francois Millet, “The Angelus”, featuring a peasant couple praying in the middle of a field. The pose of the figures in that painting appeared a number of times in Dali’s own paintings, and it seems to be echoed in the poses of the couple in the sand. Dali found “The Angelus” to be symbolic of female sexual aggression, which he tied into his own associations between sex and death. When I considered that, the transition from a happy young couple to a dead young couple imitating "The Angelus" became even more disconcerting.