Praying mantids have depth perception, based on each eye seeing slightly different images, an ability they require for their remarkable facility on bicycles. Of course this is a 1986 observation and old news for the usual crowd at the Old Entomologist, where it inspires the monthly "Magic-Eye Autostereograms for Anthropods" competition.
It is not known which algorithm they use in their little insect neural ganglia for the computation disparities. It may be the classic Marr-Poggio iterative / cooperative algorithm from 1976. Marr and Poggio originally designed this for perceiving the separate layers of wedding cakes. Trufax!
here are some scientists making dinky little polarised-filter glasses for praying mantids and showing them 3D movies. It turns out that the movie has to feature an appropriate subject and plot,
like maybe a giant female mantis who eats humans and is totally hawt, otherwise the subjects describe the 3D experience as a 'gimmick' and not worth the extra $6. Research continues into how much extra they are willing to pay for Sensurround sound, high-frame-rate, and Odorama.
The spiders are feeling left out of this research, but I don't know what they have to complain about, they still get all the best drugs. Also they are not called upon to squirt out egg-cases half the size of their abdomens and shaped like Lego blocks.