Sea spiders are an ancient group of animals that have a number of odd traits. Perhaps the most notable is that many of them either have teeny tiny hearts or no hearts at all. This has led many researchers to question how they get their blood to move around their bodies but, to date, nobody has been sure. Now a new experiment is revealing that they manage this vital task with guts... literally. Peristalsis, the process that moves food through our intestines, appears to be the primary force that swishes oxygen-carrying blood around the bodies of sea spiders. You can read more in The Economist article that I wrote on this here.