The course covered a lot of diverse topics, but I just wanted to share my three favorites with you. First, though, a bit of terminology. “Symbiosis” simply means living together, not necessarily good or bad. What we usually refer to as symbiosis is specifically mutualism. This is where both parties benefit. If one benefits and the other is unaffected, it’s commensalism. And parasitism, as we all know, is one benefiting at the expense of the other. Those symbioses are no fun and they don’t make my list.
1. Glowing squid
|The bobtail squid hosts bioluminescent bacteria |
[image from kahikai.org]
However, unlike many other bioluminescent forms of sealife, the bobtail squid can’t produce
light on its own. Instead, it collects a very specific bacteria, V. fischeri, inside its body. The squid feeds the bacteria, and in return they produce the luminescence that keeps the squid safe. Classic mutualism. And complex too. The exclusion of all bacteria that AREN’T V. fischeri is a fascinating process. Even more impressive is the fact that this has to be repeated every day -- the squid ejects all the bacteria at dawn, and when night falls the process starts all over again.
2. Three-way relationship
|Representing pea aphids as well as |
the beauty of mutualism
[image from moonbattery.com]
This is actually a four-way relationship if you count the parasitism of the wasp. But as I said before, parasitism isn’t making my list of favorites.
3. Human Guts
|Probiotics aim to restore healthy gut flora|
Our understanding of the microbiota in our guts is pretty limited at this point. But it’s becoming increasingly clear that intestinal flora plays a very important part in keeping our bodies healthy. In fact, its role can be so significant that some scientists have deemed humans to be “superorganisms” composed of both human and bacterial cells. That’s a bit of a stretch, but it’s undeniable we wouldn’t be the same without these symbiotic partners. They boast an impressive range of abilities, from assisting in the digestion of foods that our own cells can’t process, to modulating our immune systems, and potentially altering our moods and behavior.
|Fecal transplants transfer healthy flora to disease patients|
[image from wikipedia]
[On a side note, this was the last and final class of my 23-year career as a student. So I was very excited about it for that reason too. Three months till PhD!]