The bootlace worm in a rock pool with crabs

The bootlace worm usually measures 1–5 metres in length, but the longest specimen stretched to roughly 50 metres. Credit: www.aphotomarine.com

Toxicology

World’s longest animal boasts a potent poison

The bootlace worm’s mucus is loaded with a powerful nerve toxin.

A slimy worm that can stretch to 50 metres long may seem nightmarish enough, but experiments reveal that the bootlace worm has another formidable feature: a potent nerve toxin.

The invertebrate (Lineus longissimus), which lives on the sea floor and is thought to be the longest animal on Earth, squirts mucus when disturbed. Ulf Göransson at Uppsala University in Sweden and his colleagues analysed the mucus and isolated a peptide that they named nemertide α-1. When the researchers injected low doses of the peptide into green crabs (Carcinus maenas) and juvenile Dubia cockroaches (Blaptica dubia), the animals became paralysed and died.

The team found that the peptide disrupts nerve-cell activity in roaches and other invertebrate pests but is much less potent when applied to mammalian nerve cells. Along with related peptides from the bootlace worm, α-1 may prove to be a valuable insecticide, the authors say.