Its hard to hazard a guess. Redworms are common throughout most of the US. More than likely its a common nightcrawler.

Calling em earth eaters isnt necessarily correct. Redworms eat earth just like nightcrawlers eat OM (Organic matter, like veggies and newspaper). Major difference is that the nightcrawlers tend to drag the OM into the subsoil while redworms tend to live in the OM while consuming it.

Bryan

Welcome to GardenWeb, Puffy!

Like you, researchers have only theories on why worms are surface active when it's wet outside, so before I tell you what the research community surmises, I'd like to know why you think worms behave this way. ::grin::

Kelly S

why do worms come out in the rain? why do we humans come out to bask in the sun?we do it because we like it maybe the worms do it for the same reason they like it

Well one theory I have is that they are just tryin to get out of the water so that they can breath better. I've heard people say that worms do fine underwater, but I tried it and they are wrong ;-)

Another is just as carnationman said, they just like it. Maybe the water makes them more comfortable because they don't think they are going to dry up, so they come up for a breath of fresh air only to be turned into a sunchip.

Someone I was talkin to about it swore that that is when they mate, but I've never seen them mating on sidewalks. They always do that in my bin too, so the theory that they have to be in open air to mate was out the window.

Jim

Being an avid aquarist i can guarantee you that worms can and will survive underwater. 3 months after having stopped feeding L. Terrestis (nightcrawlers) to my tanks during a gravel vac i unearthed (graveled) 2 of them that were doing really well til the Oscars saw them. This is not an uncommon event (or so told in fish forums).

Living in the wter depends upon the o2 levels. This particular tank is a 90g. It has a huge surface area plus 2 Aqua clear 500's (as oscars tend to be VERY messy). Also the water level is left deliberately 3-4 inches below the trim to get good o2 exchange. My other tanks cant be gravel vac'd as they are moderately to well planted, In these tanks I like high Co2, however the plants produce alot of o2 in exchange.

My theory on why the come out has to do with animals abilities to predict weather events. Like a dog freaking out before an earthquake or hurricane/tornado, worms may sense that their environment is about to be innundated with water (which in large amounts can threaten their survival), they then go to an environment in which the odds favor them, much like us running to cellars and doorways. Nature is all about survival and furthering their species.

Bryan

Any worm I've ever put into a fish tank that wasn't eaten immediately turned white and died. :-( Maybe it has something to do with species?

Jim

Good theories, Jim, and good answers from everyone else.

In this instance researchers are, themselves, only theorizing, which is likely to remain the case until they learn to speak worm. With more than 4000 land dwelling worm species and hundreds of different environmental preferences among them it's not possible to say for certain why each of the worms that have surfaced during wet periods has done so.

The most popular threory, and the one likely applicable to the greatest number of species is that worms, being 75% water but having a gas permeable skin layer require very moist conditions in order to thrive. What better time to forage for food and a date on the soil surface than when it is rainy and dewy? Behaviors and surface activites strongly suggest that worms are typically drawn to the surface when it's wet rather than being driven there by some sense of threat.

Earthworms avoid high concentrations of CO2 and heavy rain events can slow O2 diffusion in saturated soils. This can leave the soil with higher than normal CO2 levels, leaving one to surmise that, in some cases, worms may be coming to the surface in search of some fresh air. Most soils, even when wet, are pretty well oxygenated, however (and rain water is pretty highly oxygenated water!), so it's unlikely that CO2 avoidance is the dominant reason for mass surfacing.

When barometric pressure changes very rapidly worms tend to react by crawling up. Up to what is not apparent, nor is why, though I think Bryan's theory of sensing potential threats in a way we humans cannot is interesting. A few years ago we had a typhoon here in the PNW during which the barometric pressure was measured at the lowest in recorded history. We documented worms massing up the sides of buildings and tree trunks. Very low pressure can mean a LOT of rain, and even our soils have their field saturation limit. Perhpas the worms recognize that rapid pressure change can mean the potential for rainfall events if biblical proportion? Why not!

As to worms breathing in oxygenated water, that is definitely true and well documented! Fresh water fish tanks in schools around the country now regularly play host to earthworms introduced by school children as fascinated by this idea as we. In nature many worm species thrive in saturated soils for extended periods, and a few species seek out saturated soils specifically as their preferred environment. The earthworm has an amazing ability to attach oxygen, even under very high pressure circumstances. If fish can live in the water an earthworm, in terms of oxygen need, will have no problem.

As to why the worms you placed in your fish tank died immediately, that is a good question! I've never experienced or heard of what you describe happening to worms added to fresh water tanks. Interesting!

Kelly S