1. Why do ants walk in a straight line ?
2. What is blood rain ?

When an ant finds some food, it picks a small piece of it and while returning, it leaves chemical scents called pheromones along the trail. ... As the ants follow the smell, they tend to walk in a straight line. In addition to this, we even see ants bumping their heads or colliding with each other while walking.
Blood rain or red rain is a phenomenon in which blood is perceived to fall from the sky in the form of rain. Cases have been recorded since Homer's Iliad, composed approximately 8th century BC, and are widespread. Before the 17th century it was generally believed that the rain was actually blood.