This Marine Worm is Longer Than a Blue Whale!

Did you you know there is a worm that can grow up to 180 feet (~55 meters) long! Sounds far-fetched, but this worm is one of the most common marine worms found along the coast of Britain. Known as the bootlace worm, it is a species of marine ribbon worm which can release an extremely toxic mucus and preys on crustaceans and other invertebrates.

(Dr. Mary Gillham)

Lineus longissimus is one of the longest known animal species, though it usually reaches lengths of 50 feet or less, and is only around an inch wide. Found along the coasts of Britain, Sweden and Norway, the worm feeds uses its proboscis to feed on algae and small sea creatures. This proboscis (an elongated mouth-like organ) is eversible, meaning it can be turned inside out, and is ringed with groups of adhesive filaments at its end to disable prey.

(Dr. Mary Gillham)

The bootlace worm has a brown body with light brown stripes running lengthwise from head to tail. Like other species of ribbon worms, L. longissimus can contract their bodies to a tenth of their full length when threatened, and can expand to more than double their normal width in order to swallow prey.

Its thick and highly neurotoxic mucus is used not for predation, but as a defense against predators. Reported to smell like sewage, the mucus contains peptide toxins that can paralyze crustaceans and other invertebrates, but it is not known to harm mammals (including people). Some scientists hope to use one of the more powerful of these toxins, called nemertide α-1, to create an insecticide for agricultural use. These toxins work by impeding the function of sodium ion channels, causing electrical signals in the nerves and muscles of affected species to fire without interruption, causing paralysis.

Normal Sodium Channel Function. (CNX OpenStax)