 The world is a rough place, and sometimes you just need a friend to help you out. Today, we'll be taking a look at five pairs of species that have decided they're stronger together than they are apart. This is a story of symbiosis. Don't forget to subscribe so you never miss an upload, and let's jump in. The first duo on our list are Sea Anemones and Hermit Crabs. Sea Anemones like to hitchhike on the back of hermit crabs, squaring a ride across the seabed and dining on the crabs leftovers. And the crabs don't mind these scavengers. In fact, they actively recruit them. A crab will walk up to an enemy and poke it with its pincers, signaling the enemy to release its grip from the C4 and jump on the crab's back. From there, they protect each other to the bitter end. The enemies use their barb tentacles to fend off hunger octopuses and other predators that can pierce through the crab's tough shell. And the crabs return the favor by driving away creatures that like to eat the enemies, like starfish and fireworms. It's a shared protection strategy with some free food on the side. And these two aren't the only ones sticking together under the sea. Danger, danger! That's what the frenically flapping tail of a gobie fish says to the near-blind snapping shrimp. In a crafty collaboration, snapping shrimp construct and maintain burrows in the seabed, while the gobie fish stand guard. During the construction of their home, shrimps have to leave the security of their burrow to dump the sand they dug out. Throughout this hazardous journey, these shrimp maintain constant contact with their gobie fish using their antenna. When the gobie fish sees a potential threat, it starts wiggling its tail against the shrimp's antenna or into the burrow's entrance, warning the shrimp of the impending danger. In return for their faithful service, the gobie fish get to share the burrow and call it home, sleeping with the shrimp at night and using it as a convenient shelter in the face of danger. But the ocean isn't the only place species work together. African oxpeckers have an interesting relationship with most of Africa's large mammals. They were once thought to be totally helpful, eating the ticks off the backs of zebras, elephants, hippos, and other large African animals. While they do eat ticks, their real purpose is a bit more nefarious. They're actually vampire birds, sucking the blood out of the open wound ticks create. They show how the line between symbiotic assistant and parasite can be blurred, although it seems most mammals put up with their blood-sucking behavior in exchange for their service. They also act as an early safari warning system by producing a hissing scream when startled, warning of incoming danger. So far we've talked about some pretty big partners, so how about we turn to some tiny ones? If you think humans invented agriculture, think again. Ants have been farming fungi for around 50 million years, wetting, mulching, and fertilizing their crops. Fungus farming ants originated in South America and from there spread throughout the new world tropics, from Argentina all the way to the southern United States. Perhaps the best known and most photogenic of the bunch is the leaf cutter ant. The leaf cutter ant doesn't actually eat the leaves they collect. After all, then they'd be called the leaf eater ant. These ants bring their leaf clippings to fungi deep in their nests. The fungi grow and eventually get eaten by the ants. In this partnership, if you can call one species raising another just to eat it a partnership is incredibly close. If an ant introduces a leaf to the nest that's toxic to the fungi, they'll create warning chemicals that the ants can detect. Now that we've gotten those guys out of the way, let's turn to perhaps the most legendary and the most consequential symbiotic relationship of all time. Over a billion years ago, one type of bacteria ate another, or at least they tried to. Surviving this ordeal, the prey, the humble mitochondria, became a permanent house guest in the wet, sheltered, food-rich environment of the predator's body. The mitochondria, no longer having to worry about defense from the outside world, specialized itself and became the powerhouse of the cell. Eventually, by swapping segments of DNA, the two bacteria merged into a single inseparable complex cell. This partnership was so successful, descendants of this original cell flourished, ultimately becoming the ancestor for nearly all multicellular life, including our own species. These five pairs of species show that despite the doggy dog world out there, sometimes it's best to have a friend. Even if they tried to eat you or just want to suck your blood. Well, I hope you enjoyed getting smarter with us today. If you did, be sure to like and subscribe so you never miss an upload. And remember, there's always more to learn.