The small spiders used in the film were Avondale spiders (Delena Cancerides), a harmless species from New Zealand that were provided by Landcare Research in Auckland. Despite their fierce appearance, this spider is docile member of the crab-spider family and are, in fact, harmless to humans. They were not allowed back in New Zealand for quarantine reasons. The giant "spider" used in the film was a species of a bird-eating tarantula, which attains an 8" legspan or more. Those types of tarantula are not easy to handle and can give a nasty bite. The spiders in the film were managed and handled by famed entomologist Steven R. Kutcher.
Canaima is the name of the avenging spirit of the Guyana Indians. It's also the name the area in Venezuela where the beginning of the movie was filmed and home to the world's tallest waterfall, Angel Falls.
The species in the film are Eusocial with a hierarchy reminiscent of ants and bees, in reality there is no species of spider that is purely Eusocial, most spiders are solitary with only a handful of species living in groups.
The trivia item below may give away important plot points.
In the film the species of spider are Eusocial (Division of labour, division of reproductive labour, overlapping adult generations and cooperative brood care) but in reality most species of spider are solitary and aggressive to other spiders. The social species just live communally and don't show all the traits of Eusociality.