Noticed extra-long worms in Calgary lately? You're not alone

Some extra-long worms forage about after recent rain in Calgary's Nose Hill Park. (Josh Pagé/CBC - image credit)
Some extra-long worms forage about after recent rain in Calgary's Nose Hill Park. (Josh Pagé/CBC - image credit)

Have you noticed a lot of worms around lately? And have some of them looked extra long?

You're not alone.

The folks behind the Calgary Eyeopener have been remarking on the creepy-crawly creatures amid the recent wet weather, and they got curious.

So they called up Pete Heule. He's a live-animal supervisor and noted "bug guy" at the Royal Alberta Museum. (And yes, he knows worms are not insects. "Bug" is being used pretty loosely here.)

You can listen to the full interview in the media player above.

Alternatively, here's an abridged version of his conversation with Eyeopener host Loren McGinnis.

LM: Good morning Pete, good morning. Lots of worms out in Calgary right now. Why do they come out when the ground is wet?

PH: They are always at the risk of drying out on a sunny day, so they tend to stay away from the light, stay away from the surface and come up at night time. But on a cloudy or a rainy day, they no longer have that risk of being cooked by the sun. So they can actually come up to the surface and they can forage.

And they're coming out on those cloudy days to be able to hang out on the surface and look for those dead and dying leaves and other organic matter they like to eat.

LM: OK, so let's talk about these worms. There's lots of them out and we've noted that some get really long.

PH: This is the introduced European earthworm, Lumbricus terrestris, and the adults can be 30 centimetres long. So, it could be that we're seeing a range of different sizes and it's just kind of surprising when you actually see a full grown adult out there.

If you go out at night and you actually do some digging, that's when you see the really big guys. These are the same ones that people call night crawlers.

You know, prior to the Ice Age, we would have had a great diversity of earthworms across North America. But with that huge three-kilometre thick sheet of ice scraping most the stuff off the northern part of the continent, we no longer had earthworms and we haven't in these areas for something like 10,000 years.

The earthworms came back in with European settlers, with imports of dirt, with our European plants that we're putting into our gardens. We've ended up kind of distributing them around these areas that have been without them for so long.

There is some concern that when they move out of urban centres and into our natural environments that they can actually cause some serious changes. Our forests are adapted to have a really thick layer of leaf litter that many of our different creatures use to overwinter, sort of like a leaf blanket that they can hide out underneath the snow in. And if the earthworms get into the boreal forest and they eat all that leaf litter, now we're going to have some serious trouble about who's going to be able to survive the winter.

But in your garden, in the urban centres, they're totally good. They're turning the soil, they're helping to take those organic nutrients from the surface. And then when they go back down into their burrow once it gets sunny, they essentially poop out those nutrients below ground, but that's not what these forests, you know, have adapted to be able to deal with for the last 10,000 years.

LM: Ten-thousand years of worm history! And so, depending on where they are, they're somewhat of an invasive species? Although very welcome as composters, as you say, in our home gardens or in our yards.

PH: If you're taking them for bait, then just make sure that when you're done fishing, if you have extra earthworms, take them back and chuck them in your garden. Don't dump them in the bush. Don't put them in the forest. Don't help them spread any further to where they haven't been for so long. Put them back in the garden or the compost heap, where you're happy to harness their helpfulness.

LM: Is it true that if you cut a worm in half, it turns into two worms?

PH: It depends on your definition of worms. So we tend to use worm for just about every invertebrate that lacks legs, and they are not all related to each other.… [These] worms do have a front end and a back end. They've got a mouth, a head end with brains and a back end with a butt. And they're not going to do any better learning to eat with their butts than we are. So cutting them in half, you have killed that worm, unfortunately.

But a flatworm, which is a very different creature, you can cut that guy into two and he can grow into two worms. But that is not somebody who we're trying to encourage in our gardens by any stretch, right?

LM: Where are flatworms?

PH: All over the world. Some of them are parasites. They can get into your liver and into all kinds of different animals. It's a really, really huge group of organisms most people only encounter in like, biology labs. And I think that's where the whole, 'Oh, if you cut this thing in half and you are able to put it into a relatively clean environment, it doesn't succumb to infection or get eaten by something in the meantime, it can grow into two.' But the flatworms are a completely different group, vastly unrelated to our segmented worms that the earthworms are related to.

LM: You started off talking about how they come out because they don't want to dry out. What happens when the ground eventually dries up? What happens to the worms?

PH: They're very sensitive to those different moisture levels. And so they can tell when things are drying back out, and they will essentially try to head back down on the ground. And even over the winter, they're essentially going down below the frost line. And depending on conditions and where we're at in the continent, where we are in the world, they may be able to remain active, down deep there.

I mean, they've made it all the way to Alaska and our northern territories. So, essentially you can end that the winter kills off all the adults and babies and stuff, but they're able to lay eggs in these little slimy cocoons underground that are quite resistant to freezing. So in some places it may be that essentially winter kills off everyone who's out and active, but then a fresh hatch comes in the spring. So there's a whole bunch of different possibilities that they've got.

They can also go dormant, and that's probably what they're doing around Calgary and Edmonton. I imagine they go under the ground, but they're not probably still roaming around. They're just secreting a nice little slime blanket and sleeping out the winter.

LM: Pete, you know a thing or two about worms. Good to talk to you. Thank you.

PH: My pleasure, man.

LM: That was Pete Heule. He's with the Royal Alberta Museum. My goodness, did I ever learn a few things about worms just now.