The Naked Scientists

The Naked Scientists Forum

Author Topic: How do Earthworms move?  (Read 8705 times)

paul.fr

  • Guest
How do Earthworms move?
« on: 23/07/2007 21:58:04 »
Surely they are not strong enough to push dirt / soil out of their way, so how do they move around in compacted soil?


 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
How do Earthworms move?
« Reply #1 on: 25/07/2007 03:25:11 »
as if they were in the eye of some hungry robin.

What type of worm did you have in mind - earthworm, flat worm, tube worm, boring worms, worms ad nausium?
 

another_someone

  • Guest
How do Earthworms move?
« Reply #2 on: 25/07/2007 07:19:08 »
Surely they are not strong enough to push dirt / soil out of their way, so how do they move around in compacted soil?

What do you mean "they are not strong enough to push dirt"?

How much dirt do they need to push - they are only small - they are not trying to shift enough for a human being to move through, just a few millimetre wide channel (and they will try and find the weak points to push through - they will not lift a large stone, but move around it).
 

Offline chris

  • Neilep Level Member
  • ******
  • Posts: 5339
  • Thanked: 65 times
  • The Naked Scientist
    • View Profile
    • The Naked Scientists
How do Earthworms move?
« Reply #3 on: 25/07/2007 09:33:53 »
Part of the way that earthworms move is to eat what is in front of them, pass it through their bodies and then dump it out of the back end. This is why you see "worm casts" on the grass wherever there's been a lot of worm activity.

To get about more generally they use an arrangement of muscles very similar to the system that propels your lunch through your GI tract. Our intestine is a hollow tube surrounded by two layers of muscle. One layer is "circular" muscle, which is arranged in rings around the gut lumen (the tube) and causes the central cavity to narrow when it contracts. The other layer consists of "longitudinal" muscles, which run along the length of the bowel making it short and fat when they contract. These two movements are used to generate peristalsis, which pushes the gut contents along.

In a worm, which is effectively an incompressible bag of liquid, these same movements cause the worm to become long and narrow, or short and fat. In other words they are antagonistic and the worm uses them to push itself along.

It also has one other trick to help it slither along, which are pairs of tiny hooked hairs - setae - that project from the underside of the worm at an angle and behave like miniature anchors, giving the worm extra purchase upon whatever surface it is moving. The hairs are visible if you look closely, but an even neater way to spot them is to listen to them! If you put a worm on a piece of paper and listen carefully as it moves about you will heat the setae scraping across the paper surface.

Chris
 

The Naked Scientists Forum

How do Earthworms move?
« Reply #3 on: 25/07/2007 09:33:53 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums