Which came first, a lot of sponges, or an oxygenated ocean deep? Researchers at the University of Ex

Which came first, a lot of sponges, or an oxygenated ocean deep?Researchers at the University of Exeter suggest it’s the former and as a result, the humble sponge may have paved the way for the evolution of complex lifeforms.In a paper published in Nature Geoscience, the research team hypothesises that the evolution of the first animals could have played a key role in the widespread oxygenation of the deep oceans. This in turn may have facilitated the evolution of more complex, mobile animals.Of course, a hypothesis is only as good as the evidence that supports it, and there is actually some interesting supportive considerations. Oxygen in the atmosphere first appeared nearly 3 billion years ago, but for over 2 billion years very little of that oxygen mixed into the oceans. But then in comes the sponges! DNA anlaysis has shown that the earliest sponges emerged over 700 million years ago; when the oceans contained little oxygen. After this point and over the next 100 million years, the oxygen content of the oceans increased gradually.Secondly, the eating habits of sponges also support the hypothesis. Sponges, as you can guess, are filter feeders; sucking in particulates of organic matter from the surrounding water. Yum! As rotting micobes consume oxygen, the sponges, through their appetite, remove the burden of these de-oxygenators, increasing oxygen levels in the water.This increase in the oxygen content set the stage for more complex life to emerge; it is widely accepted that the first terrestrial animals evolved from marine species.Of course, the lineage from sponge to human is a long one, but this research suggests that sponges are the most likely candidate to have gotten the show on the road!Some nice info to soak up. Pun intended.JeanImage: Yellow tube sponge, Aplysina fistularis, the purple vase sponge, Niphates digitalis, the red encrusting sponge, Spiratrella coccinea, and the gray rope sponge, Callyspongia sp. Caribbean Sea, Cayman Islands. May 23, 2007. WikicommonsMore info: http://www.livescience.com/44018-sea-sponges-oxygen-ocean-life.html -- source link

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