What is an individual?

Viewing the world as a human, I look out into the world and see myself as an individual, within a family and within a community and then as a member of the larger population of our world. A super organism of human and other life forms?

I would think of myself as a single organism. But where are the boundary lines? Biologically my body is made of millions of cells, living and dying thoughout my lifetime, I am full of bacteria and micro-organisms that are essential for my health and sometimes not so healthy existence. An organism may be either unicellular (a single cell) or, as in the case of humans, comprise many trillions of cells grouped into specialized tissues and organs. When we look further into the cell we see the nucleus, a specialised and contained region that contains the genetic material, the blueprint for cells and its multi cellular form.

This raises the question, Is an organism defined by the DNA contained within the nucleus?

Well not completely!

As a eucaryote organism, my cells also have DNA that resides outside the nucleus, the DNA is situated within small organelles called mitochondria that look spookily like little bacteria. The Mitochondria are the power generators of the cell, essential to our existence. Possibly the ancestors of the mitochondria were early cell invaders back in the mists of time, parasites, which then evolved a more symbiotic relationship with its host. Now millions of years later, the cell has become a permanent home for these 'bacteria' within our cells. Although still hosting some of its its unique coding DNA, evolution has occurred and now the nuclear DNA also codes for proteins that are required for the mitochondria's existence as well. The original parasitic mitochondrial ancestor would have been defined as an organism in its own right, but now the mitochondria has lost that identity. The distinction of an individual and an organism become harder to define when we look at some strange creatures that exist in our world.

Mixotrichia Paradoxia is one of these strange creatures that exists in symbiosis with four other organisms that provide critical structures or metabolic processes that Mixotrichia lacks. As a good analogy it is similar to thinking about your own body with the legs and arms provided by another creature. Looking down the electron microscope the Mixotrichia looked like may other singled organisms but the thing that give it away as being a little bit unusual was that it had BOTH cilia and flagella, apparently that is a no no in these kinds of cells. This encouraged scientists to look a bit harder, delving more thoroughly they realised that the flagella and cillia were actually separate organisms in their own right.

Mixotricha has four anterior flagella, that are used for steering, these are a paramecium. Movement is achieved by the beating movement of 250,000 hairlike stuctures which incredibly, were found to be helical bacteria, these are attached to the cell surface and provide the cell with cilia-like movements. Mixotricha also has rod-shaped bacteria arranged in an ordered pattern on the surface of the cell but no one knows what they do! Last but not least, Mixotrichia has spherical bacteria inside the cell which function like mitochondria.

So is Mixotrichia  and its symbionts, one individual, or many, one organism or many, a beautiful composite organism? This intriguing collection of creatures interacting symbiotically to define the the characteristics of Mixotricha paradoxia is a wonderful thing.

The definition of the boundaries of what is an organism becomes even more blurred, when you look at the larger scale and the perspective becomes even more interesting. Mixotricha paradoxia is an essential organism within the gut of the termite that allows it to obtain nutrients from wood and plant material, Mixotricha, allows the termite to exploit its barren environment, using poor food sources to sustain life. Most importantly, the termite relies on being a member of a larger community of termites in the termite mound, all working together as super organism to create the successful termite community.