The reason of how deep-sea creatures survived after the asteroid impact that killed the dinosaurs, microorganisms, invertebrates and other giant marine reptiles 65 million years ago remains a mystery until now. A new study published on April in the journal Geology reveals that these deep-sea creatures fed on algae and bacteria which were not affected by the disaster.

Previous theories state that the impact greatly reduced the extinct creatures’ food supply, including the free-floating algae and bacteria. However, a chemical analysis of fossilised shells of sea surface and sea floor organisms in the South Atlantic by a team led by researchers from Cardiff University’s School of Earth and Ocean Sciences reveal that organic matter, at that time, transferred to the sea floor from the ocean surface, thereby serving as abundant source of food to deep-sea creatures.

Apparently, the ocean food supply was restored more than half the length thought or 1.7 million years after the asteroid disaster. This allowed food chains in the ocean to resume to normal more quickly.

sea creatures

Giant isopod, thought to be abundant in cold, deep waters of the Atlantic, Pacific and Indian Oceans. Photo from Wikimedia/Laika ac

“Our results show that despite a wave of massive and virtually instantaneous extinctions among the plankton, some types of photosynthesising organisms, such as algae and bacteria, were living in the aftermath of the asteroid strike,” says lead researcher Heather Birch, a Cardiff University Ph.D. from the School of Earth and Ocean Sciences. “This provided a slow trickle of food for organisms living near the ocean floor which enabled them to survive the mass extinction, answering one of the outstanding questions that still remained regarding this period of history.”

The asteroid, per se, did not drive many species to extinction. Instead, the debris from the impact blocked the sun’s energy at the same time trapped greenhouse gases that increased the world’s temperatures.

The period is also known as the Cretaceous-Palaeogene extinction event. Moreover, the impact would have also filled the atmosphere with sulphur trioxide that caused acid rain, acidifying the ocean.