Symbiosis

I just wanted to take a quick moment and talk about symbiosis. I know it’s a topic you learn about in school; I first learned about it in middle school, then again in high school biology, and then a few more times in college. If you already know about symbiosis feel free to pick another post from the sidebar or glance over this one for a quick refresh. For those of you who haven’t learned about it yet or have simply forgotten, I’ll try to explain it in the best way possible—through the human experience!

There are many forms of symbiosis that we see and experience every day, but first let me explain what it is.

Symbiosis is any long-term and personal relationship between two or more individuals, and the relationship can be between the same or different species, such as between you and another human or a pet. Each participant in the symbiotic relationship is called a symbiont.

There are different types of symbiosis that are defined by the kind of interactions between symbionts. If you’ve read my post about coral and zooxanthellae, you’ve already been introduced to a form of symbiosis called mutualism. In a mutualistic relationship, such as coral and zooxanthellae, both parties benefit without inflicting harm on each other. Think of mutualism as the relationship you have with a project partner: if done right you both benefit from each other’s hard work. It can also be viewed in a relationship between humans and dogs or cats: the animal gains a home and a reliable food source while, the human gets companionship and additional health benefits.

A female oceanic whitetip shark (Carcharhinus longimanus) is accompanied by a group of pilotfish (pilot fish: Naucrates ductor) as it swims overhead. Photo taken by Dr. Alex Mustard, find more of his photos at www.amustard.com

Commensalism is a type of symbiotic relationship wherein one individual benefits and the other remains unaffected. An example of this is the pilot fish that ride on or near sharks or larger fish: the pilot fish feed on the leftovers of their hosts while the hosts remain unaffected. In the human experience, it’s like when you let a classmate copy off your homework: you gain nothing while they get all the right answers.

Not every relationship is healthy though. And this last relationship may be disturbing for some people.

Parasitism occurs when the parasite benefits from the host and the host suffers. An example of this relationship can be found in all species of parasitic wasps. The wasp will find another insect (caterpillars, spiders, other wasps, etc.), paralyze them, and then lay their eggs inside the host. The host will then go about the rest of their lives while incubating the eggs, and when the eggs hatch, they burst from the host like a scene from the movie Alien. And sometimes the host will survive only to protect the hatchlings until the host dies of starvation. This is an extreme example, but one of the more fascinating ones I learned about in one of my ecology classes. In human terms, parasitism is like the one cousin (or friend) that always comes to you asking for money and claiming they’ll pay you back but they never do.

Mutualism, commensalism, and parasitism are the main types of symbiosis. There are others that I will probably mention as I talk about the various other species, or if I want to dedicate another post to symbiosis. I know it’s a lot of word vomit, but I hope I made a bit more palatable than standard textbook explanations. Personally, I find symbiotic relationship like parasitism really interesting, especially with parasitoid wasps. I could easily see myself studying the wasps that may have inspired the Xenomorphs from Alien in an alternate universe!

In another alternate universe, I think I’d dedicate my life to researching sloths too. Sloths are maddeningly adorable, I could spend hours watching them. I wish there was a way to watch what my alternate selves were doing with their lives. Wouldn’t that make for some fun reality TV!

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