what is the largest worm in the world?

Worms are a pretty big and diverse group of animals and I'm not sure which is biggest (might also depend on whether you mean longest or heaviest!). If you're thinking of earthworms which are all segmented Annelid worms then I think that the largest ones in the world come from Australia and get to about 1m in length.

There are definitely bigger worms out there though and some of the marine pogonophora worms, which live near volcanic vents in the deep ocean can get up to 1.5m long.  there's some info about them here:


There are certainly several species that reach close to 1 m in length and when stretched out can get significnatly longer (though this is not normal and so does not really count).

Some parasites like tapeworms can reach huge sizes. Even human tapeworms can easily get to more than 3 m long, and I can only assume that those living in large animlas like elephants, cows and even whales would be much, much bigger.

Good point, I forgot about tapeworms. I couldn't resist a quick search ... and according to one website

"The longest tapeworm ever removed from a human came out of Sally Mae Wallace on September 05, 1991.

In all, doctors pulled 37 feet of tapeworm out of Sally Mae Wallace's body through her mouth.

If you find all of this disgusting, be glad you're not a whale as tapeworms in whales can grow up to 120 feet long."

Last edited by Alistair Wilson (31st Jul 2007 15:49:07)

Hi Gasper,

I am sorry that I cannot be more specific at the moment, but I am trying to get a more complete answer for you.  In the meantime, while watching a documentary two nights ago footage was shown of a marine polychaete worm (an annelid, or true worm) that was the diameter of my little finger, and over 80feet long (about 25metres).

I need to get you more information and will add to this answer when I can.

However, until then...... here is a website  about some of New Zealand's animals including some on the largest of New Zealand's worms.  It is the North Auckland worm Spenceriella gigantia, which reaches 1.4 metres (55 inches) long and 11 mm in diameter (http://www.terranature.org/gigantism.htm).

I will try and get you the rest of the information that I have talked about soon.