Reference: Portyankina, G., 2005. Atmosphere-surface vapor exchange and ices in the Martian polar regions. PhD thesis, ISBN 3-936586-47-0
Method: Search limited to latitudes south of 75◦S. All MOC NA images in the PDS archive that cover regions inside this area were checked visually for the presence of spider patterns. Images that contain single spiders, spider arrays, or spider ravines were selected for further analysis. Each of such images was counted as one entry. The archive covers the period from September 1997 to March 2004. We found 326 images that contain spider patterns.
Feature: The name ”martian spiders” was introduced by the MOC team to describe structures that show several branches diverging from one common center. Soon after the first detection they were discovered to be negative topographical features (depressions) – i.e. radial troughs or channels.