Scientists recently found three animal species living two miles below the surface of the Mediterranean Sea, where the super-salty waters don't have oxygen . They're multicellular , which means their bodies have many cells. They each are as small as a large grain of sand. But they are animals. The most exciting thing about these creatures, say the scientists, is that they obviously don't need oxygen to live. What biologists know about life so far is that only single-celled living things can live in places that have no oxygen, and that multicellular organisms  can visit these places, but not live there. These newly found creatures could _ . Finding animals down there was so surprising that the scientists couldn't believe it. At first, "we thought they were dead bodies," Roberto Danovaro, a scientist at the Polytechnic University of Marche in Ancona, Italy, told Science News. To find out whether the animals could actually live there Danovaro and his colleagues brought up more samples  from the ocean floor. Studying the animals in the new samples showed that they appeared to be alive. The researchers did more tests, and found that some of the animals had eggs--which suggests they were reproducing . Also in the samples were old skins, suggesting that the animals had lived there long enough to grow. Finally, pictures taken showed that the insides of the animals appear to be adapted to live in an environment that has no oxygen. These clues suggest the animals don't need oxygen, but the evidence  is indirect, which means that scientists still have not observed how the animals live without oxygen. This means more studies are needed, but the scientists think they're on the right track. And if they're right, biologists will need to rethink what they know about where animals live. More studies are needed to prove  _  .
where single-celled animals can live how the newly found animals live without oxygen whether the multicellular creatures can live underwater why the super-salty waters have no oxygen