Robert Irwin, 14, first introduced Fallon to a herd of baby African pygmy goats named after the cast of Friends who rushed toward the comedian as he fed them milk from a bottle.
Fallon then met Cookie, a Kookaburra, which is a skilled hunter.
"They're predators, everything's based on movement, so any little animal they see that's moving they're right on it, and they attack," Robert Irwin said. "So don't make any sudden movements.
After bringing out a capybara, he was joined by his mother, Terri Irwin, and sister Bindi Irwin to examine an American alligator with Fallon. The late-night host ended the segment by kissing the alligator on the head.
Steve Irwin was recently honored with a posthumous star on the Hollywood Walk of Fame. Known as "the Crocodile Hunter" for his popular TV show of the same name, he was a zookeeper and wildlife documentarian. He died in 2006 after a stingray pierced his heart while he was filming underwater.
"It was such an amazing honor, really, a true honor for us because he's really one of the only conservationists honored on the Walk of Fame, so it's great to continue his message and really keep his dream alive," Robert Irwin told Fallon.