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Heteromastus filiformis


up to 18 centimeters, with a thickness of 1 mm


blood red


bacteria living in the mudflat bottom


fish, crabs, shrimp, catworms, shorebirds



  • Dut: Rode draadworm
  • Lat: Heteromastus filiformis
  • Eng: Heteromastus filiformis
  • Ger: Kotpillenwurm (Drahtwurm, Schnurrwurm)
  • Dan: Heteromastus filiformis (capitellider)
Rode draadworm, Koninklijk NIOZ,
Tekening van

Heteromastus filiformis

Heteromastus filiformis is a long thin bright red worm. The animal is filled with hemoglobin, the same pigment which colors our blood red. We use hemoglobin to carry oxygen. The worm uses it for the same reason. This allows the worm to live in parts of the mudflats where there is very little oxygen. The worm burrows itself into a vertical tunnel, head first. It eats up sand containing bacteria, its main diet. The digested sand is excreted onto the flats and looks like black-gray pills.

  • Distribution and habitat

    The Heteromastus filiformis lives in the Wadden Sea, delta region and river mouths, in fine sand or mud.