March 28 – Long Time Slime

Today’s Factismal: At 177 ft, the bootlace worm (Lineus longissimus) is the world’s longest animal.

Imagine, if you will, a piece of licorice that is nearly twice as long as a basketball court but only about half an inch across. Now imagine that the “licorice” is writhing about and exuding a smelly, toxic goo. Paint your writhing mass of poisonous licorice brown with light brown racing stripes, and you’ve got a bootlace worm, the world’s longest animal.

A Bootlace Worm offshore England (Image courtesy Gordon Lang)

A Bootlace Worm offshore England (Image courtesy Gordon Lang)

Also known as the giant ribbon worm or the ribbon worm (though that is more of a generic name), the bootlace worm is a member of the sea-going worms known as the Nermerteans. These critters all have a rudimentary “brain” consisting of four nerve clusters, up to twenty pairs of light-sensitive “eyes”, a gut that runs the length of the animal, and (most amazing of all) a nose that they poke in and out as they stab at their prey. Nermerteans are found in all oceans and a few species even live on land, but the bootlace worm is limited to the North Sea, where they are plentiful.

A bootlace worm offshore Norway (Image courtesy XX)

A bootlace worm offshore Norway (Image courtesy Sor-Trondelag)

Amazingly, the 177 ft measured for the bootlace worm may not be the longest it can get – many Nermertean species can extend themselves by as much as ten times their normal length! Of course, even for the bootlace worm, 177 ft is exceptional; most specimens are a mere thirty feet long. That length serves the bootlace worm well as it searches for prey to grab with the “fingers” at the end of its “nose”. These stretchy scavengers live in tide pools, along rocky shores and mud flats. Though they can reproduce sexually, cutting them into pieces (for example, when a fish tries to turn one into dinner) will also make new bootlace worms from each piece.

Though the bootlace worm may seem icky or gross, it is a vital part of the local ecology and can tell us much about the local ocean health. If you’d like to help monitor your local ocean, then why not join a Beach Watch program like these in Texas and California?

4 thoughts on “March 28 – Long Time Slime

  1. not sure I believe this one
    Cantell (1976 – Zoologica Scripta. 5:117-120) states that it has been reported in the scientific literature to 10 meters. Unattributed comment that it may get to 30 meters – but no reference.
    I’m still pushing for Praya (the siphonophore) measured at 40 meters as the longest animal…..

    • I think that Praya may count as the longest colonial animal. But I can understand why you are so fond of the critter; after all, it was MBARI that saw just how long they were! 😎

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