Could Jupiter Moon Harbor Fish-Size Life?

And the extraterrestrial ocean is currently being fed more than a hundred times more oxygen than previous models had suggested, according to provocative new research.

That amount of oxygen would be enough to support more than just microscopic life-forms: At least three million tons of fishlike creatures could theoretically live and breathe on Europa, said study author Richard Greenberg of the University of Arizona in Tucson.

(Related: "Did Rising Oxygen Levels Fuel Mammal Evolution?")

"There's nothing saying there is life there now," said Greenberg, who presented his work last month at a meeting of the American Astronomical Society's Division for Planetary Sciences. "But we do know there are the physical conditions to support it."

In fact, based on what we know about the Jovian moon, parts of Europa's seafloor should greatly resemble the environments around Earth's deep-ocean hydrothermal vents, said deep-sea molecular ecologist Timothy Shank.

"I'd be shocked if no life existed on Europa," said Shank, of the Woods Hole Oceanographic Institution, who was not involved in the new study.