THE Rotifera are remarkable among the Metazoa for their small size, often smaller than the largest ciliated Protozoa. Many rotifers are colourless or at most show some slight colour in the gut ...

Morphological studies have proposed various hypotheses linking acanthocephalans to Platyhelminthes (flatworms), Priapulida (penis worms), or Rotifera (wheel animals). However, molecular ...