On both land and sea, the sun is the primary source of energy in most ecosystems. Plants or algae use sunlight to create food through photosynthesis. Animals eat the plants and algae, and then get eaten themselves by predators higher up the food chain. Without the sun providing a base amount of energy input, most ecosystems would swiftly collapse. Even so, there are some animals that live beyond reach of the sun’s rays.

How can life exist in the deep ocean without getting energy from the sun?

A vestigial structure is a body part or organ that was useful in an ancestor, but is diminished in size, complexity, or utility in their descendant. Many animals have vestigial structures, like the small spurs on pythons that once were legs. Humans have vestigial structures too, and they give us a tantalizing glimpse into our evolutionary history.

Life gives us a lot to get stressed about. I won’t tell you not to worry, but if you are, consider some of these scientific methods to ease your stress.

Hamsters were the pet of my childhood and I was often kept awake at night listening to the squeaking of the wheel as they ran. Were my pets really enjoying themselves, or were they running because they were driven to neuroses by the boredom of captivity? Two researchers put the running wheel to the test. They placed them in the wild, where rodents have the whole world to engage and entertain them. Would they still be drawn to the wheel, or is wheel running something for caged rodents only?