Fighting was the job of the Gladiators. There were several types of gladiators who engaged in different types of fight. When they did not fight they trained. Most of them were slaves and belonged to their trainer or rich men.
micro-organisims such as bacteria.
animals such as cats and dogs
They can test on almost anything. Why they test on animals right now, I don't know.
Criminals did not usually fight gladiators. Gladiators fought other gladiators; the crowd would not tolerate anything less. If a criminal were to be executed by means of "gladiatorial" combat, he was paired against another criminal and the two men would be given swords and perhaps a shield, but little else.
Hair extensions can be made out of several different animals. Horses are one of the leading animals.
"Else"? Besides what?
What else besides what?