Changes in stool color alone do not cause symptoms. The underlying cause of the change in stool color, texture, or form is responsible for any symptoms. Bowel movements are usually light to dark brown in color, and there is moderate variation among individuals with respect to stool color, quantity and form.
Plants in the Twilight Zone As the amount of light decreases, the size and complexity of plant life also decreases. So whereas there may be flowering plants growing in the entrance zone, the twilight zone is typically marked by mosses and ferns.
This zone is divided further into three subzones. The sunlit zone is where photosynthesis takes place. Plankton and jellyfish are drifters that inhabit this zone. Most animals living in the open ocean live in the sunlit zone. Twilight zone. Below the sunlit zone is the twilight zone where some light penetrates the ocean to a depth of 3000 feet.