Human impact can cause population decline as previous limit are removed. Carnivores prey on animals.
The epiglottis is a flap in the back of your tongue that prevents food from entering the larynx. When your mouth is closed, the epiglottis is in place and blocks the larynx opening. If your mouth is open, the flap lifts and the larynx is no longer blocked so you can breathe. This is why it's important to not chew with your mouth open... if you do, then food can go down the larynx by mistake.
When the circular muscles contract, the earthworm stretches, becoming longer and thinner. The earthworm uses its setae to anchor the front of its body in the soil. Now the longitudinal muscles contract and the earthworm becomes shorter and wider or it bends from one side to the other, pulling the body forward.
Answer: If enough evidence accumulates to support a hypothesis, it moves to the next step — known as a theory — in the scientific method and becomes accepted as a valid explanation of a phenomenon.