Spiders come under the category of "Arachnids" whiles insects come under the category of "insecta" The differences are that they are kept under different "classes" in the Animal Kingdom.Insects are categorized to have three pairs of legs and three segments of body parts;while Arachnids are categorized to have four pairs of legs and two segments of body parts.
Other examples of Arachnids are Scorpions,mites and ticks(found on the hair/skin of dogs/humans)
Yes,for students of Biology they have to have knowledge regarding various classifications under the section of "Animals
" and "Plants"
It is sometimes very confusing to see new terms and byheart such terms as "classification",I can understand the plight of these students as I myself studied Biology and Zoology during my intermediate (after 10th class ) :)
