thrives because it's hidden. making it easy to expand the violent greed. we wanted to show the world who was happening. if you're alarmed by this, this is how you can show your support. >> this is not just our world. we're sharing it. it may sound obvious but every specy that is vanishes from our planet is gone. forever. >> i started to really find out and examine exactly what was going on and it's devastating. >> the illegal wildlife trade is the fourth most lucrative global crime after drugs, human trafficking and arms worth between $5 billion and $20 billion a year. the nonprofit organization african parks estimates that central africa has lost 62% of its forest elephants in the last decade. the crime is becoming more rampant all the time. cnn's arwa damon joins rangers