Deep sea creatures are evolutionary question marks. They live in conditions that would be unlivable for most organisms, and still cover some "95% of Earth's living space," according to the Smithsonian. They're more like space aliens than fish, but their deep sea habitat apparently contributed to the heartiness of their ancestors — when an asteroid hit Earth 65 million years ago, it killed off the dinos but not the inhabitants of the deep sea. Now, scientists at Cardiff University have a theory as to why.
"Our results show that despite a wave of massive and virtually instantaneous extinctions among the plankton, some types of photosynthesizing organisms, such as algae and bacteria, were living in the aftermath of the asteroid strike," Heather Birch, who led the research team at the university's School of Earth and Ocean Sciences, said. "This provided a slow trickle of food for organisms living near the ocean floor, which enabled them to survive the mass extinction."
As the BBC reported, it was generally accepted that the "asteroid cut off the food supply" for the ocean's animal population, which is why its hulking sea reptiles and various organisms perished with the dinosaurs. Studying fossilized shells drilled from the South Atlantic's floor, Birch and her team suggested that the sinking stream of algae and bacteria still alive after the asteroid fed the creatures at the very bottom of the ocean for nearly 2 million years, until their food stores were fully restocked.
The study, published in the journal of Geology, appears to answer a question over which science has long been scratching its head. It's one mystery of the deep solved, but don't worry — many more remain.