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Shrimp cleaning teeth
A shrimp enters the mouth of a fish to clean its teeth. Fish value this service because shrimp can remove and eat harmful parasites. When fish need a cleaning, they approach the anemone in the background, in which the shrimp lives, and open their mouths, encouraging the shrimp in. Both partners benefit.
A rotating amusement park ride at dusk. Passengers on this ride experience a force about twice that of gravity. The force is due to the acceleration felt by the change in direction necessary to keep the passenger moving in a circle at a constant speed. The same force applies to satellites orbiting planets and planets orbiting the sun.
How thick is your brain?
The thickness of a brain's gray matter varies across the brain. Here it is color-coded, from red (thickest) to blue (thinnest). Made up of nerve cell bodies, gray matter is thickest in the frontal lobes of the brain, at the top. Researchers believe that the frontal lobes control languages, memory, judgment and social skills.