What’s the most important marine lifeform?

Well that’s a question isn’t it. What do you think, whales and dolphins will spring to mind for so many people, but I did not ask what the most intelligent marine lifeform is, so what is it. Are they corals for without them reefs would not exist and our landmass would look totally different, are they the algae’s the basis of 99% of life in the oceans, well it could be, but another organism is in contention as well. One that possibly has more effect on carbon dioxide levels in the ocean than anything else – so now it is hugely important.

This beast collectively has a direct impact on the world’s oceans pH levels, it is important hugely important in the carbon cycling of the ocean and is a major player in the production of oceanic methane, a greenhouse gas 20 x more effective than carbon dioxide. Our beast has no name—it’s only known as SAR11 the most abundant marine organism known.

Their combined weight will exceed all of the fish in the ocean, think of that, yet a single millilitre could contain 500,000 individuals, we have the smallest marine bacteria discovered, yet the most abundant marine lifeform known.

So we have a saturated sea of floating bacteria, the simplest bacteria known, yet they all need food and in doing so take in carbon compounds and convert them to other organic compounds and CO2 as waste, so we can see how hugely important these are in the maintaining of the carbon cycle.

However they don’t just need carbon to function they also need phosphorus and when this is in a low concentration they turn to a compound called methylphosphonic acid. The breaking down of the compound produces methane gas which is now in a saturated state in many areas of the world’s surface waters.

So our beast is the most abundant lifeform in the oceans (and we can’t see it!). It is the most important player in the cycling of carbon, its importance in methane production is only just being uncovered, yet it is being destroyed at an incredible rate. No no no—for once we humans might not be to blame, but the bacteria’s age old nemesis, the killer virus, it latches onto the cell, infects the cell, kills the cell, which then splits and sinks to the abyssal depths taking all that carbon with it, – more carbon cycling to understand! One great thing here is that the bacteria are always one step ahead, every time the virus mutates to get more effective the bacteria develop another defence to stay ahead.

So the most biologically important beast in the sea could be the simplest bacterial cell known to man, it exists in mind boggling numbers that it outweighs all the fish, it is in a constant battle for survival in a biological war for supremacy of the microbiological world. The next time you accidently take a sip or mouthful of sea water think of how many SAP11 bacteria you have just taken out of the equation!