A new study reveals details about the role worms play in metal cycling in shallow marine environments, such as tidal flats and estuaries. The research focuses on the burrows of a worm known as Diopatra cuprea. These marine invertebrates secrete a mucus that plays a role in metal binding and helps to stabilize burrows. Researchers examined the surface reactivity of the tube, or parchment, created by the worm. Materials produced by other organisms have indicated that the surface of the tube can be reactive, and absorbs metal cations that the animal uses for nutrition. However, in the case of D. cuprea, it appears that the linings are not reactive and are likely to serve as protection from physical dangers like predation.

The burrowing action of worms in shallow marine settings is thought to play an important role in recycling organic carbon in these environments. Studying shallow marine ecosystems is of value to astrobiologists because these ecosystems have persisted throughout much of life’s history on Earth, and understanding how modern systems work can help scientists interpret biosignatures left by ancient life in the rock record. One implication drawn from the study is that because the mucus-lined burrows of D. cuprea have a low reactivity toward metals, they may not leave a trace in the geological record. Trace fossils left by D. cuprea, and possibly similar animals, may be indistinguishable from surrounding rocks.

The study, “Diopatra cuprea worm burrow parchment: a cautionary tale of infaunal surface reactivity,” was published in the journal Lethaia: An International Journal of Palaeontology and Stratigraphy. The work was supported in part by NASA Astrobiology through the Exobiology Program.