Scintillating Scotoma. (Migraine Scotoma). A scotoma is a âblind spotâ in front of the vision. The visual phenomenon of scintillating scotoma usually appears like a âtwinkling shadowâ or âzig zag patternâ before the eyes.While every experience is a little different, the most common symptoms are âblack spotâ or âtwinkling blurâ appearing before the eyes.he visual phenomenon of scintillating scotoma usually appears like a âtwinkling shadowâ or âzig zag patternâ before the eyes. While every experience is a little different, the most common symptoms are âblack spotâ or âtwinkling blurâ appearing before the eyes.
Cancel. Spiders live all over the world, including trees, dry areas, wet areas, under ground and in the oceans. Discover the different varieties of spiders on the earth with information from a science teacher in this free video on spider habitats.ancel. Spiders live all over the world, including trees, dry areas, wet areas, under ground and in the oceans. Discover the different varieties of spiders on the earth with information from a science teacher in this free video on spider habitats.
True spiders have been found in Carboniferous rocks from 318 to 299 million years ago, and are very similar to the most primitive surviving suborder, the Mesothelae. The main groups of modern spiders, Mygalomorphae and Araneomorphae, first appeared in the Triassic period, before 200 million years ago.