Mouse spiders have burrows. Their burrows are can be more than 3 ft. deep. Although you rarely see females out of their burrows, male spiders often come out in the day (usually after rain),and the reason why they come out is because they are in search of a mate. These spiders are commonly found In South America.
If a mouse spider feels threatened it WILL bite. Mouse spider's bites are very painful. Mouse spiders have venom.
Mouse spiders eat mostly bugs and other spiders but sometimes eat small vertebrates such as mice and frogs.
Mouse spiders can get up to 1 1/2 inches in length. The males are smaller than females. Males have bright red head and are referred to as "red headed mouse spider".
Arthropods are a group of animals/bugs with invertebrates such as, millipedes, spiders, hermit crabs, ect. They are rather amazing but in terms of species they are second to none. Also almost all arthropods have multiple limbs. And mouse spiders are part of the arthropods family.