Hi
Zoo radio was a phenomenon before reality TV, with so called shock jocks such as Howard Stern.
--- does it say that the radio called "Zoo" or "zoo" appeared on the market before reality television and that such people like Howard Stern worked for this radio?
cheers
That is what it is saying.
"Zoo radio" is a genre or style of radio program; in the US, it's usually the early morning "drive time" program (from about 6AM until 10AM). It's called "zoo" because it's a free-form, "anything goes" type of format - they feature "zany" disc jockeys who stage weird contests between listeners, make prank telephone calls to celebrities, discuss bizarre stories in the headlines that day, etc.
Howard Stern is a classic example of a "shock jock" or "zoo radio disc jockey." He'd have, for example, two women simulate lesbian sex on the air, or send his cohort Stuttering John out to red carpet events in New York City to ask celebrities embarrassing questions on the air.