The subarachanoid space lies between the arachnoid and pia mater. It is filled with cerebrospinal fluid. All blood vessels entering the brain, as well as cranial nerves pass through this space. The term arachnoid refers to the spider web like appearance of the blood vessels within the space.
Why do biologists organize living things into groups? What do the levels of classification indicate about the relationship between organisms? What characteristics are used to classify organisms into domains and kingdoms? What is the scientific study of how living things are classified called? Taxonomy
We refer to the scientific classification system as taxonomy. It classifies everything in science into a number of different categories. There are a couple different forms of taxonomy. If you do a quick Google search of the term, you will find that taxonomy might apply to chemicals, animal species and more.