The bootlace worm (Lineus longissimus) — the longest animal on Earth — produces a neurotoxin that can kill both crabs and cockroaches, a team of Swedish scientists has discovered.
The bootlace worm (Lineus longissimus). Image credit: Cédric Audibert / AnimalBase Project Group, www.animalbase.uni-goettingen.de.
The bootlace worm is a member of Nemertea, a phylum of invertebrate animals also known as ‘ribbon worms’ or ‘proboscis worms.’
The species is usually 15-50 feet (5-15 m) in length, but can be up to 180 feet (55 m) long, usually only 5-10 mm in width.
When the bootlace worm is irritated, it releases large amounts of thick mucus that is poisonous for crustaceans.
Professor Ulf Göransson of Uppsala University and co-authors extracted the most prevalent peptide toxin from the bootlace worm’s mucus and discovered that it could paralyse and kill crustaceans and cockroaches.
“We already know that peptide toxins are found in, for example, cone shells that live in tropical waters,” he said.
“Bootlace worm live in colder waters, for example, the coastlines of Great Britain and Norway and the west coast of Sweden.”
“This peptide toxin, named nemertide α-1, is the most poisonous substance to have been found in Sweden’s animal kingdom and the fact that it may be possible to use it makes the discovery even more exciting.”
Toxins often affect the ionic channels, that is, proteins that control the transport of different ions in and out of cells.
Professor Göransson’s team showed that the isolated toxin impedes the inactivation of the sodium channels in three species of invertebrate animals: the German cockroach, fruit fly and Varroa mite. That causes continual electric signalling in nerves and muscles, which gives rise to paralysis.
Laboratory tests were conducted to investigate how the toxin affects the sodium channels of mammals. There, the reaction was not nearly as strong.
“Therefore, we believe nemertide α-1 is probably not poisonous for humans or other mammals,” the researchers said.
“Today, similar neurotoxins that have been extracted from snakes, spiders and cone shells are used, for example, as pharmaceuticals, pharmacological tools, in biotechnology and as agricultural insecticides.”
“We believe that the toxins from the bootlace worm can also be used to develop new insecticides.”
“Nemertide α-1 has a very powerful effect on crustaceans and cockroaches, which is why it could serve as a very effective insecticide,” Professor Göransson said.
“From a research point of view, it’s exciting to have discovered a new toxin in our own fauna, in a group of animals that has basically never been explored. Moreover, the whole chain of research can be attributed to our team’s effort, from discovering the substance in the bootlace worm to describing the structure of the toxin and studying its effect.”
The team’s findings were published in the journal Scientific Reports.
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Erik Jacobsson et al. 2018. Peptide ion channel toxins from the bootlace worm, the longest animal on Earth. Scientific Reports 8, article number: 4596; doi: 10.1038/s41598-018-22305-w
