Huge Viruses Are Shaking Up The Tree of Life
Pandoraviruses are challenging some long-held biological beliefs. These newly-discovered beasts are larger, in size and in genetic complexity, than any other virus that we know of (details on the graphic are below). They are not as doom-worthy as their name implies, but they may have opened a box full of new biological forms that will challenge what we think of when we say “alive” or “virus”. For the scientific low-down on pandoraviruses, check out this great article by Carl Zimmer.
Giant viruses of all kinds seem to be more common than we’ve ever imagined. It makes sense, in a way. Just like there is not a clear transition point between any two species, the complexity of life should also exist on a continuum from the small (bacterial viruses) to the complex (us). So maybe these little guys aren’t so surprising after all?
I drew up a little graphic (above) to show just how large and complex pandoraviruses are compared to other life forms.
- Pandoraviruses are huge. A human egg cell is about 100 millionths of a meter across. An E. coli is about 50 times smaller. But pandoraviruses (which dwarf flu viruses) are nearly as big as the bacterium!
- The area of the circles show how many genes each type of cell contains. The human genome has about 20,000 genes, while E. coli has about 4,500. Compared to a measly 13 genes in the flu virus, pandoraviruses have about 2,500!, almost none of which seem to be related to known genes.
- The size of the genome, in bases, is where it gets weird. The human egg’s genome, at 3 billion bases, dwarfs them all. E. coli and pandoraviruses have around 4 and 2 million, respectively. And there’s a tiny little single pixel in there representing the 13,588 letters of the influenza genome.
I can’t wait to see what other kinds of life/not life we find inside this Pandora’s box.