Cyclocosmia or “trapdoor spider” is a genus of spiders in the Ctenizidae family.

The abdomen of spiders in this genus is abruptly truncated and ends in a hardened disc which is strengthened by a system of ribs and grooves. They use this to clog the entrance of their 7 to 15 cm deep vertical burrows when threatened, a phenomenon called phragmosis.

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