Interaction among species

Lina is very hungry. Oh no! The fridge is empty, what happened?! - Leon! What am I going to eat?! Brothers are the worst!

Sometimes food and other resources are limited. What can you do? You can compete for them, or share and co-operate. It works the same in nature where different individuals live together in the same area. Sometimes organisms work well together, sometimes they ignore each other, and sometimes they fight.

Let’s see how it works! Some individuals help each other to become stronger and safer. They can warn and protect each other, find food, or hunt. If a meerkat sees something dangerous, for example an eagle, it warns other meerkats, so that they can hide in tunnels they have built together. They are safer, because they cooperate!

Sometimes individuals of one species cooperate with individuals of another species. To thrive, or even to survive, one of them needs the other. And sometimes, they both need each other. This is called symbiosis. When a bee eats nectar from a flower, pollen from the flower sticks to the bee.

Flowers help bees to get food, and bees help flowers to produce new plants. The help is mutual - both bees and flowers gain something useful from each other. This kind of symbiosis is called mutualism. When one of the organisms gains something from a situation but the other doesn’t gain or lose anything, this can also be symbiotic. If a bird builds a nest in a tree hollow, the tree does not win or lose anything.

But the bird and its eggs gain a shelter to live in. This kind of symbiosis is called commensalism. Sometimes one species benefits from symbiosis, but it harms the other one. When a dog catches fleas, they live in the dog’s fur and suck blood to feed. The dog is hurt but it can’t do much about it.

A flea lives on its host - a dog - as long as possible. The flea is a parasite. This kind of symbiosis is called parasitism. Some organisms don’t cooperate with anyone and they usually have to fight for what they need. This is called competition.

For example pine trees in a forest compete for nutrients from the soil. They also fight for space to grow, and for the sunlight they need to produce energy. They compete with other pine trees - members of the same species. This is intraspecific competition. When different species fight for the same resources, for example different kinds of birds feeding on the same kind of grain, it’s called interspecific competition.

There are also species that kill other organisms to get food. For example, eagles hunt smaller birds. This is called predation. Species that eat other organisms are called predators. Interactions between organisms happen all the time, and play a very important role.

But not all organisms living in the same area interact. Some species avoid competition. For instance, giraffes have long necks, and eat leaves from the top of the trees where only a few can reach. They have a niche and they have adapted to it. Giraffes also have patterns on their bodies, so it’s difficult for lions to see them.

This way, they avoid predation. Leon knows he is in trouble. But he has a cooperation strategy too! - Lina, look! I made you a sandwich! Hm, maybe having a little brother is not so bad after all!