Evolution of the first animals may have played a role in the oxygenation of the deep oceans. This in turn might have led to the evolution of more complex species, says a new research.

Research by the University of Exeter unveiled that sponges seem to have added more oxygen to the deep ocean. This factor would have helped in making the environment congenial for the evolution of more-oxygen using animals.

Lead author Tim Lenton has carried out DNA analysis. At least, 700 million years ago, the earliest sponges had most probably emerged, revealed the analysis. At that time, the oceans did not have much oxygen. But between 700 and 600 million year ago, the oceans have been more enriched with oxygen.

During the time, when sponges fed their pores, they filtered out tiny particles of organic matter from the water. These particles might be having dead microbial matter that rots and consumed oxygen. But sponges helped in cleaning water of this material and without rotten culture, the water might have experienced more oxygen levels.

The new research is based on the recent work of researchers in Denmark. In their work, scientists said sponges required small amount of oxygen.

"We argue that the evolution of the first animals could have played a key role in the widespread oxygenation of the deep oceans", said researchers. Increased oxygen-rich environment led to the ideal conditions where more mobile animals can evolve as these animals required higher oxygen levels for survival.

The study published in the journal Nature Geoscience has provided a reasonable mechanism for ocean oxygenation and that too without the need of a rise in the atmospheric oxygen.