Question of the Week

What do Worms do in the Rain?

Sun, 11th Apr 2010

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Question

Sarah, West Sussex asked:

Ever since the heavy snowfall in January, the water meadow I pass most days has been more water than meadow.

 

What I would like to know is, how do the worms cope?

 

Can they really breathe and survive conditions that range from almost totally dry to what must be utterly soaked and saturated for days to weeks at a time?

Answer

We put this question to Kevin Butt from the Earthworm Research Group at the University of Central Lancashire...

Kevin -    Okay, worms are quite amazing creatures really.  Unlike many other creatures, they obtain their oxygen through their moist skin.  They don't have anything like lungs or gills unlike other animals.  This means they can get the oxygen they need from the air which is the normal situation.  But equally, they can get their oxygen from water because obviously water is H2O containing oxygen.  So if the earthworm is underwater, it can get oxygen just as easily as if it was in the air.  And experiments have been undertaken keeping earthworms underwater for days on end, and they come to no harm.  Some people think that if a worm is buried and gets flooded, then they would seek to escape.  But as I just mentioned, they don't need to because they can get the oxygen they need from the water.  However, quite often we see earthworms on the soil surface or on pavements seemingly trying to escape from inundation of water.  But perhaps, it's not that.  Maybe it's something slightly different - that the animals are actually trying to make use of the moist conditions in order to move away from their burrows, if you like, to pastures new so that they can mate with individuals that are not closely related to themselves.  Not only can the earthworms survive well in the wet conditions, they can survive well under dry conditions in the soil, if it's really, really dry.  And they do this, perhaps, by creating a spherical chamber in the ground, lining it with their own mucus, curling up almost tying themselves in a knot and just sitting there and waiting for better conditions to come along.  And many species of earthworm do this.  Others like the lobworm, the big worm that is in Britain, burrow deeply down into the soil and just avoid the dry conditions near the surface.

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I think worms breath through their skin, taking oxygen from water. So that would mean if there is no water, they would just dry up and die.
I'm not sure if too much water would cause them to drown or just move out until a better balance of water quanity came about. echochartruse, Thu, 1st Apr 2010

My experience with worms comes from having a worm compost. I know that worms are fasinating, to me any way. Their 'eggs', not sure if that is what they are called, can stay in dry ground for a long period of time and hatch when conditions are right. I noticed with my worm farm, spring was a time when populations exploded. I'm not sure if it was the food I ate and gave the scraps to the worms due to seasonal change or if it was the climate conditions. All I know is that they are very good at reproducing throughout the entire year. echochartruse, Thu, 1st Apr 2010

Worms in a waterlogged area will move out or drown. They need to be moist, but not wet, as this kills them. If you water a spot where there are worms until it is soaked, then continue until it becomes waterlogged, the worms will surface, irrespective of any other conditions, as they are drowning. SeanB, Thu, 1st Apr 2010

Sorry SeanB, it seems our expert disagrees! BRValsler, Thu, 15th Apr 2010

I read an interesting article recently about people who harvest worms. They use a technique called "grunting".

They drive a wooden stake into the ground then drag a piece of steel along it so that the wood resonantes (hence the term grunting). Apparently, the worms think the noise is caused by a mole coming after them, so they head for the surface as quickly as possible. Geezer, Thu, 15th Apr 2010

I posted a worm question a few weeks ago - not one sensible response - it concerned thousands of worms on pavements up to 400 yards from my house - still waiting for an answer... old_bob, Wed, 16th Mar 2011

I recommend that you ask your public librarian what books by Charles Darwin are available on the subject of earthworms. You can find a lot of his work on earthworms online. Phractality, Wed, 16th Mar 2011

They don't use molecular oxygen in H2O. They utilize oxygen DISSOLVED in the water . Mr Inchpractice, Thu, 13th Feb 2014

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