Between bacteria and archaea (another type of single-celled microbe), there are more than 1030 individual cells. Although most are about one micrometre long (0.001mm), it’s such a colossal number that laid end-to-end, they would stretch for 10 billion light-years!
This bacterial thread would still be difficult to see, because one micrometreis about 75 times thinner than a human hair. But if youwrapped the thread aroundthe Milky Way, itwouldencircle itmore than 20,000 times, creating a2cm-wide ribbonthatmight catchenoughlight to be visible to the naked eye.
Statistics like this show just how bad we are at visualising large and small amounts. Ten billion light-years is an unfathomablelength, but if we packed all the bacteria into a cube (and it didn’tcollapseunder its own weight) it would only be around 10km on each side, which seems much more manageable.
In reality, up to 80 per cent of all the bacteria in the world are found in biofilms
on rocks, in the soil, on stagnant water and in virtually every other habitat, including yourmouthand intestines. These biofilms are a few hundred bacteria thick and can contain bacteria, archaea and fungi of various species banding togetherina kind of city.
You can see biofilms whenever you clean your house. The red, black or brown slime on your shower head, under the rim of the toiletor on the draining rack on the kitchen sink are all bacterial biofilms,eachconsisting oftens of millions of bacteria.
Read more:
- Am I more bacteria than human?
- Is there anywhere that’s completely bacteria-free?
- Could eating bacteria help you lose weight?
- Put down the disinfectant: Should we be encouraging helpful bacteria into our homes?
Asked by: Tom Shepherd, Bristol
To submit your questions email us at questions@sciencefocus.com (don't forget to include your name and location)
