Animals use smells to "talk" to each other and to protect themselves in the world. Some animals have noses for smelling, and others use an organ that works like a nose to sniff or sense information. Animals can also release smells to send a message to other animals. A scent can be used to help find food, communicate, mark an animal's territory, find a mate, and keep away another animals.
Animals That Use Smells
Science has found that most animals have a sense of smell, but the organ they use to smell can differ wildly from one animal to the next. Each basic category of animal has its own unique way of smelling. For instance, amphibians like frogs use nares, which are holes starting in the mouth and leading to the face, like human nostrils. Fish also use nares, taking in water that moves over sensory pads in their heads that tell their brains what they are smelling. Birds smell through nostrils found on their beaks. Mammal nostrils, on the other hand, are located on the nose. Mammals have a large range of smell, and some are better at it then others. Dogs, for example, are very good at sniffing, while elephants are even better; both of them can smell better than humans can.
Insects use receptors on their bodies that contain pores, or holes, that pick up scents from the air. Reptiles like lizards are even more unusual because they use their tongue to smell. They flick their tongue to pick up scent particles from the air, and when their tongue goes back into their mouth, it rests on the roof of the mouth, where special sensors interpret the scent.
Communicating With Scents
Animals use scents to send messages to each other, so their sense of smell can be very important. For instance, some animals will release a unique scent to mark their territory, telling other animals that smell it that this area is taken and they need to move along. Animals can also use scent to attract possible mates, using smells that contain chemicals called pheremones.
Some animals even use smells as a trap, releasing a scent that attracts animals that they plan to eat! On the other hand, many animals use their sense of smell to find food. And some animals use smells to keep from becoming food themselves: Animals like skunks shoot out stinky smells when they're threatened to make predators run away.
Using Smells for Protection
Lots of animals mark their territory with smells to warn others away and keep their home safe. And skunks aren't the only animals that use their scent as a weapon to stay safe. Vultures vomit a particularly smelly substance when they are threatened: In fact, they actually throw up at their target, hitting them with their vomit, which not only smells bad but can get in their eyes and sting them. Millipedes can release a seriously smelly and irritating spray to ward off attackers. The bombardier beetle bombs an enemy with stinky smells. Opossums don't just play dead when they are threatened: They also give off a gross smell to go along with this performance. And even stray cats, especially males, can releasing smelly liquid when they are under stress. One of the most interesting ways to use smell as a weapon, though, comes from the sea hare, a type of sea slug. It can squirt out ink onto its predators that hurts their ability to smell, so suddenly, the sea hare smells much less delicious!