While effort has been taken to ensure the accuracy of data here, accurately sorting animals into useful and navigable groups without making a mess of it is beyond the scope of a site like this. Some animal groupings, such as separating arachnids and spiders, is to help non-experts find animals of interest, rather than to be strictly accurate.
Also, poisonous means something you eat. Snakes and spiders are venomous. Just saying.
