Here is a nice reconstruction of one of the most popular activities which took place in the ancient amphitheatres (here the Colosseum): the venatio! What was it?
Imagine one or more hunters standing in the arena, people who had just one purpose: to capture, and kill, animals of various species. By the herbivores such as deers or gazelles, rabbits or hares, to the ferocious animals such as lions, panthers or tigers. But even something more incredible and large powerful animals such as bears or even elephants. The men that were in the area were true hunters, or people trained specially for the purpose who used to dress a specific short tunic, that was perfect in order to move faster and easier. The venatores used to have just one weapon, a spear, that sometimes was used to kill in a short time the beasts. But there were not real rules, so much that, for example, thanks to some records we know that there were venatores who tried to kill animals like bears without weapons, using just the hands!
A venatio was a pure entertainment for the ancient romans, who in this way were able to admire exotic animals, something that was absolutely unknown at our latitudes (such as lions and gazelles). So the empire could show itself as capable of anything, since it is powerful, prosperous, and immensely. The emperor, in particular, could demonstrate to his subjects that it was able to bend to its rule, the Nature of the same, transporting to Rome, and in large quantities, animals that otherwise never would have been able to see in our latitudes. Not only this because the venatio was embellished with a scene that is curated to the very last detail: the turf, caves, knolls, hills, or trees were transported inside the arena through trap-doors, underground, and winches operated by slaves. One thing that was really exceptional for the time. The venatores (so the hunters) were also often clothes with short tunics decorated with bright colors, feathers, or other. Why? A way to exorcise an eternal battle between civilization (Rome and its empire), and all that is wild and not civilized (like the animals).
Furthermore, the insertion of a scene, which often follows that of the native land of the animals that were in the area, served to make even more spectacular the games. The people, when he came to the Coliseum, had to be surprised, in all possible ways. And people must also be satisfied, and when it didn't happen it could be a problem: animals couldn't be weak or drugged, they couldn't be very old or tame. If something like that happened the spectators were not able to entertain themselves, and if they got angry it could be a problem for the personal security of the editor, the organizer of the game.
To say that, according to some sources, the first forms of venationes were organized in the course of the III century b.C., and that the practice of the venatio and the hunting was very common and very much felt in roman culture. Even if the venationes became an extraordinary political instrument for a perfect political propaganda, mainly during the imperial time, there were people who didn't appreciate them. For example Cicero, at the I century b.C. when several beasts started to be shown in Rome by powerful men like Caesar or Pompeo, expressed his ideas in this way: "They (the venationes) are wonderful, of course. But what could it be exciting in a marvelous beast that is killed?"