"I don't know what that is and I'm the expert," marvels Dr Robert Raven, the Queensland Museum's head of terrestrial biodiversity and principal scientist in arachnology.

Dr Raven is looking through a microscope at one of the hundreds of spiders he has brought back to a field laboratory set up for scientists at Birrigai, an outdoor education centre at Tidbinbilla.

The new species he has just discovered won't be the only important find made during a 10-day Bush Blitz expedition to the ACT, but mystery still surrounds how many new spiders, fish, insects, frogs and plants will be revealed before the expedition ends on December 6.

Twenty-one scientists from across Australia are working at Birriagai during this leg of the Bush Blitz, Australia's largest nature discovery project.

They're heading out on foot and by road to bring back specimens from the vast Tidbinbilla bush, Namadgi National Park, the Australian National Botanic Gardens and even the gardens of Parliament House.

To get to the most remote and inaccessible areas, they've even got a helicopter.

In 36 expeditions since 2010, Bush Blitz - a partnership between the federal government, Earthwatch Australia and BHP - has discovered more than 1600 new species, including 71 in Namadgi National Park five years ago.

Dr Raven said results like that and his own experience in Canberra, where he completed postdoctoral research in 1984, had him convinced that locals didn't know just how significant their surroundings were.

"I think the thing that I’m particularly surprised at is that there is so much diversity so close to a city like Canberra, which is a made city," he said.

"I know [Canberrans] don’t know how significant it is. I know they don’t appreciate it, because I didn’t appreciate it until a week or so ago when I came and saw what wonderful forests there are so close to the city."

He said taxonomy was critically underfunded in Australia and around the world, making the resources available during the Bush Blitz invaluable.

Bush Blitz manager Jo Harding agreed, saying that while many people didn't see the need to distinguish between different species of a certain animal, there were often important implications in a new discovery.

"If you’ve got something and it doesn’t have a name, you can’t do anything with it," Ms Harding said.

"You can’t put it on a list, you can’t share information about it with other scientists.

"If it doesn’t have a name, you don’t know if it’s the new cane toad or the cure to cancer, because no one can do the necessary work on it. It’s pretty important."

It's not just new species the scientists are looking for.

University of NSW entomologist Dr Ryan Shofner specialises on lace bugs and is often just as excited to bring back a specimen that's been known for some time.

"No one's really worked on this group since the '60s in Australia," he said,

"There's a lot that's not known, so if it's not a new species it just may have not been collected in a long time. Both are very valuable to us."

The Bush Blitz community day will be held on Sunday at the Australian National Botanic Gardens from 10am to 3pm.