 Members of the Mecysmaucheniidae also have an elongated prosoma and chelicerae, although less so than archaeids.When hunting prey, mecysmaucheniids hold their chelicerae widely open.Long, forward directed hairs (setae) appear to act as triggers; when these are touched by prey, the chelicerae rapidly snap shut, enabling mecysmaucheniids to catch fast-moving prey, such as springtails.