E-Mail IMAGE: Fragment of the anterior end of an individual living worm (Ramisyllis multicaudata) dissected out of its host sponge. Bifurcation of the gut can be seen where the worm branches. The... view more Credit: Ponz-Segrelles & Glasby The marine worm Ramisyllis multicaudata, which lives within the internal canals of a sponge, is one of only two such species possessing a branching body, with one head and multiple posterior ends. An international research team led by the Universities of Göttingen and Madrid is the first to describe the internal anatomy of this intriguing animal. The researchers discovered that the complex body of this worm spreads extensively in the canals of their host sponges. In addition, they describe the anatomical details and nervous system of its unusual reproductive units, the stolons, which form their own brain when detached for fertilization, allowing them to navigate their environment. The results were published in the