Trichuris muris is a parasitic nematode affecting mice. Following ingestion, T. muris eggs hatch in the large intestine where they develop into adults. The anterior end of the worm burrows into the lining of the gut, leaving the posterior end protruding into the lumen of the gut. The worms mate in this orientation, and the resulting eggs are released in to the gut lumen and shed faecally.
David Goulding, Wellcome Trust Sanger Institute