Only 30 per cent of Australia's estimated 750,000 species have been documented and a new push from experts in the field is calling for support to name and understand the remaining 70 per cent in 25 years - at the current rate of discovery that would take 400 years.

A significant increase in funding and training is needed to tackle the mission which would cost $824 million over 25 years.

A new report has found the economic benefits of having a true understanding of Australia's biodiversity far outweigh the cost to get there.

Australian Academy of Science director of Taxonomy Australia Kevin Thiele said Australia couldn't be managed sustainably without better knowledge of the missing species, which are primarily insects, fungi, mites and marine invertebrates.

"Imagine if you were a big company and you had no stocktake of 70 per cent of your products, you had no idea what products you had, what they do, what problems could arise. You simply couldn't work like that," he said.

On average, 1000 species each year are named in Australia, but Associate Professor Thiele said that needed to increase 16-fold to achieve the 25-year goal.

"Which is important because in 400 years many, many things would have gone extinct by the time we get there," he said.

Associate Professor Thiele said it was likely many unnamed species of insects and spiders went "extinct invisibly" in the recent bushfires.

"Conservation is obviously important to the public and the government, but we can't monitor species that we don't know about," he said.

A Deloitte Access Economics report has found $824 million over 25 years would be needed to achieve the goal, but analysis found every $1 invested could return up to $35 to the economy.

Report author Matt Judkins said benefits ranged from $3.7 billion to $28.9 billion over 25 years.

Improved conservation and increased resilience for some species, and a reduction in costly delays to identifying possible biosecurity risks, are among the benefits.

The first steps would be to create a national biobank and DNA sequence library which would ensure DNA sequences for all known species were available.

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Associate Professor Thiele said it was easy to find unknown species in Australia, but there was a lack of expertise for the difficult task of documenting them.

"If you went out into your backyard there would be unnamed species of insects or mites," he said.

"It's going to be extremely difficult to figure out whether it's a named species or not, we don't have enough expertise."

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