As many as 10,000 citizen scientists have helped discover landforms known as 'spiders' on parts of Mars where they were previously thought not to exist.

The 'spiders' are named for their arachnid-like appearance and are a type of land erosion where networks of cracks form on martian soil, completely different to anything on Earth, researchers at Oxford University in the UK said.

The discovery was made by volunteers working on behalf of Planet Four: Terrains, an online project hosted by Zooniverse, the world's largest and most popular people-powered research platform, they said.

Araneiforms - the scientific name for these features - occur at the planet's South Pole and form when carbon dioxide turns to ice during the martian winter.

As the seasons change, direct sunlight penetrates the translucent ice, warming the land beneath.

The land surface then gets eroded as the gas races out and rips off little bits of dirt, forming spindly branches which resemble spider legs.

The features were previously thought only to exist in a region known as the South Polar Layered Deposits (SPLD), banded layers of dust and water ice.

However, in a recent research published in the journal Icarus, citizen-science volunteers spotted the 'spider' formations in other areas of the martian polar surface.

The sightings were later confirmed using high resolution imaging from HiRISE (High Resolution Imaging Experiment) camera aboard NASA's Mars Reconnaissance Orbiter.

Planet Four: Terrains started in June 2015, and was one of the first citizen science projects to launch using the Zooniverse's Project Builder platform.

As many as 10,000 citizen scientists contributed to the 'spider' research, viewing and classifying over 20,000 images derived from observations made by the Context Camera (CTX), aboard the Mars Reconnaissance Orbiter.

These images contained many spiders as well as other land forms known as 'Swiss cheese terrain', and craters. "This was a totally unexpected find. By having so many eyes scouring the images, we know now that the SPLD is not the only place where spiders form.

This will help us better understand the carbon dioxide jet formation process," said Meg Schwamb, from the Gemini Observatory and lead author of the research paper.