Map the Spider

Help make a map for the Philadelphia purse-web spider

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Last on:
30 Jan 2023

The Philadelphia area has a unique spider! (see

Purse-web spiders (Mygalomorphae, Atypidae) are primitive animals related to tarantulas, and spend most of their time hidden from view in their underground burrow. Their unique 'sock-like' tubular web hangs in the burrow and reaches up above-ground where it is attached to the base of a tree, shrub, boulder or wall. Clusters of up to 20 small webs can sometimes be found together.

Purse-webs are rarely noticed because they are well-camouflaged with dirt and debris, often resembling a root. The spiders hunt from within the web, stabbing prey that contact the silk and dragging them inside to be eaten. Individual purse-web spiders can live for many years and occupy the same web. Unlike most flimsy spider webs, the durable purse-web design can withstand seasonal damage and be seen at any time of the year.

In the U.S., the strictly North American genus Sphodros has 7 species found east of the continental divide, but we also have one enigmatic species in the genus Atypus normally associated with Europe and Asia. This spider was described in 1973 as Atypus snetsingeri and known - at that time - only from one site in eastern Delaware County, PA, near Philadelphia. A recent DNA analysis (published in 2022) has shown that our unique Atypus species is actually an introduced population of the east Asian species Atypus karschi Dönitz, 1887.

No one knows how long Atypus karschi has been here, but theoretically it could have hitched a ride as far back as 1784, hidden among potted plants, when direct shipping began from China to the port of Philadelphia in the newly-independent United States of America. Searches for webs in the region have shown that the spider is not uncommon, and can be found in habitats ranging from forest and woodlands to neighborhood hedges and gardens.

This project asks people to look for and report sightings of purse-webs in the Philadelphia region to help develop an accurate estimate of the introduced spider's current range and distribution. Your observations can will help identify the 'boundaries' of the spider's range and how common it is in different areas. A good map may help unravel the spider's history here.

Use the Epicollect5 application to report where you searched and for how long, and whether or not you found any purse-webs (both kinds of data are important!). Help us make a definitive map for our local purse-web spider.

Spiders are cool, but purse-web spiders are *very* cool. See if you can find the spider in your neighborhood!
Visit the project website for more details (