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
Section 17.1 - The History of Classification. - Biologists use a system of classification to organize information about the diversity of living things. - Just as stores group CDs according to type of music and artist, biologists group living things by their characteristics and evolutionary relationships.