During the summer, here in the Adirondacks the little creatures we call earthworms are abundant and apparent. For many, earthworms are just a simple creature that are foraged for to utilize as bait when fishing, but they serve many more purposes than this. Earthworms perform several beneficial functions such as: Stimulating microbial activity.
Earthworms derive their nutrition from microorganisms, many more microorganisms are present in their feces or casts than in the organic matter that they consume. As organic matter passes through their intestines, it is fragmented and inoculated with microorganisms. Increased microbial activity facilitates the cycling of nutrients from organic matter and their conversion into forms readily taken up by plants. As they consume organic matter and mineral particles, earthworms excrete wastes in the form of casts, a type of soil aggregate. A large proportion of soil passes through the guts of earthworms, and they can turn over the top six inches of soil in ten to twenty years.
Earthworms enhance porosity as they move through the soil. Some species make permanent burrows deep into the soil. These burrows can exist long after the inhabitant has died, and can be a major conduit for soil drainage, particularly during heavy rainfall. At the same time, the burrows minimize surface water erosion. The horizontal burrowing of other species in the top several inches of soil increase overall porosity and drainage. By fragmenting organic matter, earthworms can significantly increase the water-holding capacity of soils. The channels made by deep-burrowing earthworms are lined with readily available nutrients and make it easier for roots to penetrate deep into the soil. Plant and crop residue are gradually buried by cast material deposited on the surface and as earthworms pull surface residue into their burrows. These actions and their benefits end as soon as the temperature drops.
Starting in fall, these creatures descend and disappear from view in preparation for the coming freeze. During winter, most worms stay in their burrows below frozen soil hard as rock covered with ice and snow. They coil into a slime-coated ball and go into a sleep-like state called estivation, similar to hibernation for bears. Worms will survive in frozen or dry soils by estivation until warmer weather arrives.
Not all earthworms make that downward journey to survive winter. Some kinds of earthworms lay their eggs in cocoons safe in the soil to hatch when conditions are right then settle under leaf litter on top of the soil, where they freeze and die.
There are however worms, known as ice worms, that thrive in the frigid, freezing temperatures. These earthworm relatives live and thrive in glacial ice in Alaska, Washington, Oregon and British Columbia. Ice worms are just one among other species that take advantage of ice for food and habitat. These cold weather worms survive by eating the algae and pollen that grow and fall in the glaciers and at times consuming ice and snow. They use small bristles on the outside of their body, called setae, to grip the ice and pull themselves between densely packed ice crystals with ease.
The ice worm has adapted to the freezing temperatures and functions at its best at about zero degrees Celsius but the insulating quality of snow keeps the temperature just below the surface at 32 degrees Fahrenheit. It is the heat not the cold that can cause their demise. When heated to approximately 40 degrees Fahrenheit, these creatures melt and die. On bright sunny days, these worms hide deep in the ice and snow emerging at dusk as the sun sets. They may not be here in the mountains, but across the country worms can be seen throughout Winter crawling through and thriving in the frozen landscape.
Photos by Jackie Woodcock