Earth Day 2016: we all need each other

Spring is synonymous with warmer weather and colorful blooming flowers - but it's also the time of pollination, in which some animals play a vital role for many plant species. For instance butterflies make reproduction possible for blooming plants by feeding on flowers, transferring pollen from one to another. In this sense, a butterfly on a flower actually represents new life.

Symbiosis is ever-present in nature: Remora fish have evolved to have a sucker disc for attaching to passing sharks, so they can eat leftover prey and from the shark's mouth and parasites from its skin. Sharks are kept clean and free from scraps that could end up being unhealthy for them.

Oxpeckers live in sub-Saharan Africa together with some of the world's largest hoofed mammals such as buffalo - but they know exactly how to handle them. The birds work hard to keep the beasts clean - from parasites, dandruff and even earwax - and alert them by hissing if they sense danger. This cleaning sustains the birds, and their large hosts protect them from predators.

Is it moss? Is it an epiphyte? Nope, it's lichen - a hybrid produced through a symbiotic relationship between algae and fungus. Algae produce their own food via photosynthesis; the fungus extracts nutrients from the environment and protects the algae. Thanks to this combination, lichen is very resistant and adaptable to many ecosystems. Yet it is also very sensitive to changes in air quality!

Separated millions of years ago, they are still dependent on each other. The Amazon is known as the "lungs of the Earth" - but its own survival depends on nutriments transported from the vast Sahara Desert. Satellite images, like the one above, show how a cloud of dust traveling across the Atlantic connects the largest hot desert and the largest tropical rainforest on Earth.

Hermit crabs are the squatters of nature - they live in empty seashells to protect their weak abdomens. The scarcity of this precious home often causes aggressive fights among crabs. To protect their treasure and scare predators, crabs attach sea anemones to their shell. In return, the anemone benefits from the crab's leftovers and expands its range of forage onboard the shell.

Clownfish have also taken on anemone's protection, making anemones their home: the poisonous tentacles protect them from predators and provide them with leftovers. Nemo's species helps the anemone catch prey by luring in other fish and keeping the area clean. Moreover, this useful deal results in a stylish combination of colors.

Sloths, characterized by their slowness, live in the trees of Central and South America, and eat mainly leaves. But their bodies are home to a vast animal kingdom, from moths to beetles. Their diet is low in nutrients and hard to digest - to compensate, sloth consume algae from their fur during cleaning. Algae, for its part, develops thanks to the insects' feces.