Worms can live under the water for weeks

How long can earthworms survive underwater? I keep finding them in the backyard pond, and they're usually moving around like everything's hunky-dory! I've started taking them out and putting them in the dirt, and they seem to go right on about their business. — Rita M., Medford.

So the worm turns, Rita.

Earthworms can survive underwater for weeks as long as there is enough oxygen. They wouldn't make it in a stagnant bog, for example, but then, neither would we at Since You Asked, since we could never handle the mosquitoes.

Worms respire through their skin, coating themselves in mucus to enable dissolved oxygen to pass into the bloodstream — another trick we've not mastered.

We know what you're going to say. Then why do worms always come out after rain, right?

The Since You Asked School of Invertebrate Biology reports that that's a mystery, but researchers are working on three theories. One, worms take advantage of being able to move around safely without dehydrating in the high relative humidity.

Two, they avoid getting trapped in their burrows as the rain causes microbe numbers to spike, depleting oxygen in the soil.

Three, they just want to feed the robins.

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