The Bootlance Worm (Lineus longissimus), also known as the Giant Ribbon Worm, is a strange creature which is found throughout the British Isles. It is extremely long, but less than an inch thick, and often spends most of its life in a knotted, tangled mass, disguising its true length. Its body is usually brown to black with a purplish or bluish head. They can be found across all manner of seabeds and can sometimes be found in the intertidal zone, occasionally trapped in rockpools and will often hide themselves away in cracks and crevices in rocks. The bootlace worm does not have a barbed proboscis (like ragworm) which can be extended to attack prey and instead turns its proboscis inside-out to feed. However, they are thought to be able to absorb nutrient directly through their skin (which may be why they have evolved to have such long bodies). When handled or attacked this species can produce a mucus which is powerful enough to paralyse and kill crustaceans and  is harmful to humans if ingested.

Longest Animal in the World?

A report from the 1800s states that a bootlace worm was found in Scotland which was, when untangled and fully extended, just over 55 metres (180 feet) long. This would make the bootlace worm the longest creature in the world. However, although widely cited to this day, the report was never officially verified and it has to be noted that the bootlace worm has a somewhat stretchy body, meaning that the true length of the creature could have been well under the reported 55 metres. Certainly bootlace worms reaching lengths of 10 to 15 metres are common, and bootlace worms have been verified as reaching lengths of well over 30 metres.