The Helensburgh zoo may be small but it is making a big difference along with many other wildlife parks who are bringing a range of endangered native species to the heart of Sydney to raise awareness of their plight.

It is a subject members of the Radnidge family, who own the zoo, are very passionate about.

They don't want to see more iconic native animals become extinct like the Tasmanian tiger.

John, Matt, Michael, Michelle and Margaret Radnidge want to do everything possible with breeding programs and whatever else it takes to save other species such as the Tasmanian devil from suffering the same fate.

That is why they are sending six zookeepers, a range of Australian reptiles, green and gold bell frogs, native bugs, a golden brush tail possum and Leo the albino echidna to Martin Place at the busiest time of day to reach as many people as possible.

Zoo and Aquarium Association Australasia executive director Chris Hibbard said Symbio's work in conjunction with other wildlife parks had been instrumental in ensuring the survival of the Tasmanian devil from devil facial tumour disease, which has already wiped out large populations of the species.

Mr Hibbard said the conservation work was vitally important.

"It is a day to really focus on what is happening with threatened species," he said.

"It came about by highlighting the plight of the bilby. The association pulls together our membership across Australia to galvanise support for a whole raft of threatened species because increasingly zoo involvement is becoming more and more important. The Tasmanian devil's survival is now entirely reliant on the work of zoos.

"There are now a huge number of species where zoos are now a critical part of their recovery.

"And the koala is one we have to keep a very careful eye on. We are not taking koalas in Australia for granted any longer."