article_snippet: Study builds on earlier research which looked at the genes expressed during the development of intestines, stomach and anus in the Penis worm, pictured .
article_snippet: The worm, named Xenoturbella bocki, has no brain, no sex organs and no vital organs.
article_snippet: The worm, named Xenoturbella is regarded by some scientists as a key biological link between many species.
article_snippet: Researchers believe The worm, named Xenoturbella is a distant progenitor of humans and a host of other animals living today.
article_snippet: Swedish researchers say The worm, named Xenoturbella might belong to a branch of the animal family tree called deuterostomes, of which humans are also members.
article_snippet: The latest study builds on earlier research which looked at the genes expressed during the development of intestines, stomach and anus in the Penis worm.
article_snippet: Penis worms live in shallow parts of the oceans, including off the Swedish west coast where they propagate during the winter. '