Animals cannot talk, but they send messages all the time. Ants leave a chemical trail called a pheromone as they walk, so other ants can follow it to food. If you rub your finger across an ant line, the ants become confused because the smell trail is broken. Birds give sharp alarm calls when a cat or hawk is near, and other birds, even of different species, understand the warning. Langur monkeys give one call for a leopard and another for an eagle. Elephants rumble at sounds so low that humans cannot hear them, and the rumbles travel through the ground for many kilometres.
Many animals also communicate with movement, colour and light. Honeybees perform a waggle dance inside the hive; the angle of the dance tells other bees the direction of flowers, and the length of the dance tells the distance. A male peacock spreads his tail to attract a mate. Fireflies flash in patterns, and each species has its own code. Dogs communicate with their whole body: a wagging tail, flattened ears or raised fur each mean something different. Scientists have found that animals sleep very differently too: a giraffe sleeps less than 2 hours a day, a python sleeps about 18 hours, and dolphins rest one half of the brain at a time so they can keep swimming.
Example: Find a line of ants on a wall or path. Watch how each ant touches the ant coming the other way with its antennae. Then place a small piece of fruit 30 centimetres away and time how long it takes the first ant to find it and the first ten ants to arrive. Prediction: after the first ant finds the food, the others will arrive much faster because they follow its pheromone trail.