This not-so-little glossy black spider is yet another of the many reasons to be careful of arthropods in Australia. The name refers to several species of spider, all under the genus Missulena, which were formerly believed to dig very deep burrows like mice. They are mygalomorph spiders, like tarantulas or Australian funnel-webs, with fangs that strike downward, rather than crossing as they do in araneomorph spiders. Female mouse spiders live in burrows covered with a trap door, and hunt by ambush, using silk tripwires to alert them to the close approach of the insects, spiders, scorpions and other creatures that they prey upon. The males, however, wander in search of mates and so hunt by running down their prey.
The mouse spider is not known for aggression, but the wandering habits of the males do bring them into contact with humans occasionally. They deliver a painful bite, mostly due to their large chelicerae, and are described as tenacious, refusing to let go once forced to strike. Most of the time, this is the only real effect, as they are very prone to giving dry bites. However, when they do deliver venom, their bite can be dangerous. It is exceedingly similar to that of the various funnel-web species, right down to the factors which harm humans but have almost no effect on dogs or cats. (Unlike the American tarantula, which can kill dogs, but is harmless to people). Even cases of envenomation seldom result in serious symptoms, but when they do, funnel-web antivenin is cross-reactive with the venom of the mouse spider.