Traders

The traders were extremely critical in the success in the arena. without the traders there were no animals. since the roman empire reached into asia and africa there was a wide variety of animals. the traders were hired to get the animals and transport them unharmed to rome. once the animals reached the arena the "Beast Masters" took the animals and provided them food water and a place to sleep. the beast masters were like the inn keepers for the animals

The Damage

The damage done from these games was much more than ever anticipated. some species of animals used like "The Hippopotamus were captured from the River Nile in Egypt but following the Roman era they disappeared from this habitat. Many of the great wild animals from Africa and Asia such as elephants, lions and tigers were hunted to the point of extinction. Entire species of animals disappeared from their native habitats. And the Great Auk (Pinguinus impennis), the European Wild Horse (Equus ferus), the Aurochs (Bos primigenius primigenius) and the Eurasian lynx became extinct." <From http://www.roman-colosseum.info/colosseum/wild-animals-at-the-colosseum.htm> Parenthetical is From (colosseum.com, page wild animals at the colosseum

The Bestiarii (Bestiarius)

The Bestiarii (Bestiarius) were the gladiators who fought against the animals. these gladiators had their own traditions, school, slang, weapons, and uniform just like normal gladiators. their unique school was called scholae bestiarum or the bestiariorum. slaves and volunteers trained to be a Bestiarius. 

Ludus Matutinus/venationes Animal shows.

Ludus Matutinus was the display of animals. a play involving animals usually scheduled for the morning. it was essentially a show like a play. this included fake sets and props. the animals were often trained like a modern circus act. this was to give the impression of a real hunting exploit. the animals were "The types of animals used for these hunting shows were wild boar, bulls, bears deer, stags, dogs, wolves, goats and antelopes. These shows were called called venationes and the animal hunters were called venatores. The venatores were trained at a special training school called the Ludus Matutinus. The term Ludus Matutinus originated from the Latin for 'morning school' as the beast shows were originally scheduled as morning events at the Roman Colosseum." From <http://www.roman-colosseum.info/colosseum/wild-animals-at-the-colosseum.htm> Parenthetical is From (colosseum.com, page wild animals at the colosseum

The List Of Animals

The animals used varied. some arenas only had a few animals while huge arenas such as the Colosseum had numerous animals.
Wild boar
Bulls
Bears
Deer
Stags
Dogs
Wolves
Goats
Antelopes
Buffaloes
Snakes
Camels
Donkeys
Hyena
Giraffes
Lions
Tigers
Leopards
Cheetahs
Panthers
Elephants
Crocodiles
Jaguars
Chimpanzees
Apes
Baboons
Hippopotamus
Rhinoceros
Crocodiles
these animals were captured from conquests all over the world. besides, the roman empire reached all of these habitats, therefore getting the animals is only the matter of hiring a good trader

The Beast Hunts

In some games or circuses the organizers would stage beast hunts. There would be more than one hunt going on at one time because the Circuses, like the Circus Maximus in Rome in 174 B.C. were generally so large that a person sitting at one end of the  would not be able to see clearly what was occurring on the other side. also due to the central spine or barrier limited views. later in rome arenas and amphitheaters made viewing easier and only a few hunts were going on at one time. overall the beast hunts were not connected to the central gladiatorial games. they were individual sporting entertainment events. sometimes in circuses or just shows.

The uses

The uses of animals in the arena varied greatly. some animals were used just for viewing and they didnt fight. while others such as bears, panthers, and bulls were used to fight each other of used to fight the gladiators. Lions were also used very often due to their theatrical nature. their natural signs of aggression such as roaring and bearing their teeth entertained the crowds very well.