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Listen to part of a lecture in a biology class. The professor is discussing animal communication. OK, so we've talked about visual and auditory signals in animals, but today I want to focus on a less obvious form: chemical communication. Many animals, from insects to mammals, release chemical substances called pheromones, which can trigger specific behaviors or physiological changes in other members of the same species. For example, ants use pheromones to mark trails to food sources, and when one ant finds food, it leaves a chemical trail that others can follow. In mammals, pheromones often play a role in mating. Female moths, for instance, release a pheromone that can attract male moths from several kilometers away. Interestingly, pheromones are also involved in social bonding, like in some rodents where mothers and pups recognize each other through scent. Now, a common misconception is that pheromones are always volatile—that they evaporate quickly. But some are actually quite stable and can persist in the environment for a long time, which is useful for territorial marking. So, while we often think of communication as something we can see or hear, chemical signals are equally important in the animal world.