The MRI scanner measures this signal difference and displays the activity as a colored area (Figure 1). Diffusion Tensor Imaging (DTI) is a technique that detects how water travels along the white matter tracts in the brain (Figure 2). White-matter tracts connect different parts of the brain and must be protected during surgery. A dye (contrast agent) may be injected into your blood stream.
Dock spiders can swim. A dock spider can actually swim under water and stay submerged for several minutes. It uses air bubbles trapped in the fine hairs on its body under its belly to provide oxygen while it is under water â a bit like a dock spider scuba dive. Dock spiders walk on water.
The largest spider in the world is the huntsman spider, also known as giant crab spiders. Their leg span can reach up to 12 inches long and they are perhaps the most unique looking spiders out there. Their legs are twisted in a crablike manner (hence the nickname) and they are incredibly agile when on the hunt.