When people use the word symbiosis, they’re usually talking about a mutualistic symbiotic relationship. Mutualism is a close, long-lasting relationship where both parties benefit. Organisms can use other organisms for cleaning, protection or gathering food. In some mutualistic relationships, the organisms can’t survive without each other.
Some examples of mutualism in nature include:
- Cleaner wrasse live in “cleaning stations” in a reef. They remove and eat parasites, dead tissue and mucous from reef fish, which helps reef fish stay healthy.
- Clownfish secrete a substance that protects them against the sting of sea anemones. They can pass through anemone tentacles, which keeps them safe from predators. Clownfish attract other fish which the anemones can catch and eat.
- When a fruit bat eats the fruit from a fig tree, it eats the seeds as well. These seeds are dispersed through the bat’s droppings.
- Bees gather nectar from flowers, which they make into food. Pollen rubs onto their bodies as they collect the nectar, and the pollen then falls off into the next flower, which pollinates it.
- Humans have a mutualistic relationship with microorganisms, primarily bacteria, in their digestive tract. Bacteria aid in digestion and regulate the intestinal environment, and in return, they feed off of the food humans eat.
Commensalism is a one-sided relationship where one of the organisms benefits greatly from the symbiosis. The other is not helped, but it is not harmed or damaged from the relationship either. In some of these commensalism relationships, the organism that is reaping the benefit will use the other for protection or transportation.
Examples of commensalism in habitats include:
- The cattle egret, a short bird found foraging in cattle herds, eats insects that have been disturbed when the cattle forage. It doesn’t affect the cattle, but the cattle egret depends on this food source.
- A spider uses a tree to build its web. The tree is not impacted but the spider needs the tree for shelter and safety.
- Remora fish, a type of suckerfish, attach themselves to sharks and other large fish. They detach when the larger fish feeds and eat the leftover scraps.
- Tiny pseudoscorpions hitchhike on larger insects to get from place to place. The insect is not harmed, but pseudoscorpions would not be able to travel without this commensalistic relationship.
- Many weeds create spiky burrs that attach to an animal’s hair or fur. As the animal travels, these burrs fall off, successfully dispersing the plant’s seeds.