What Is the Smallest Living Cell?

Life ranges in size from sperm whales to tiny bacteria and other microbes. However, while sperm whales play their part, these tiny microbes have a far greater impact on the environment than their larger cousins. For instance, the world's smallest living cell produces the majority of the world's oxygen and plays a huge role in the Earth's carbon cycle.

  1. SAR11

    • The smallest living cell known in existence is Pelagibacter ubique, also known as SAR11. SAR11 is the most numerous organism in the world, though SAR11 is mostly found on the ocean's surface. Even though they are the smallest, their combined weight would exceed the weight of all the fish in the ocean.

    Energy Source

    • SAR11 is the only known organism that can conduct photochemistry without chlorophyll. This is a very hardy organism that can survive in many areas where no other organisms can survive due to its multiple methods of acquiring energy. SAR11 is able to collect sunlight energy through a retinal organ, which energizes SAR11. However, SAR11 seems to have an alternative form of energy consumption, since it can survive and grow without sunlight.

    Other Characteristics

    • SAR11 has the ability to sense elements such as nitrogen, phosphate and iron. SAR11 also needs reduced sulfur compounds. SAR11 also has the world's smallest genome.

    Importance

    • SAR11 plays a role in producing 50 percent of the oxygen produced in this world. SAR11 does this through a process of recycling nutrients. SAR11 plays a massive role in the carbon cycle due to the abundance of SAR11. SAR11 is considered one of the greatest consumers of carbon.

    Junk DNA

    • By studying SAR11, researchers have discovered that the incredibly small genome that SAR11 contains demonstrates that smaller genomes lead to more efficient organisms. The fierce natural selection that SAR11 experiences suggests that natural selection aids in eliminating much of the unnecessary DNA that might work against the species' survival.