Many are cold but few are frozen
Every year thousands of attractive young lasses around the world are crowned "Miss something-or-other" at local rodeos, county festivals, youth camps - you name it. Girls vie eagerly for the honor of receiving the crown on offer and basking in the admiring looks of the boys. One wonders, though, just how many sign up to compete for the honor bestowed annually by the judges in Cordova, Alaska, at their unique town fair. There the ?lucky? girl, you see, wins the dubious title of "Miss Iceworm". I jest not.
Until a few weeks ago I had never heard of iceworms let alone of Cordova's annual Iceworm Festival, one of the most successful local fairs in Alaska. I was perusing the "Journal of Morphology" in search of useful material for an upcoming book on evolution (yes, yet another book on evolution/creation - why not?) when a particular title caught my eye: "Morphologic Characterization of the Ice Worm Mesenchytraeus solifugus". The what!? I couldn't resist taking a peek. You won't believe this, but it's true. About 20 glaciers in northwest America and Canada harbor populations of inch long worms that not only live in solid ice but can crawl easily through it. I jest not again. At their liveliest around 32° F, iceworms will freeze solid if exposed to colder air and will turn to goo if warmed up to room temperature. During winter they appear to remain firmly lodged in the depths of the ice while in summer they can be found appearing in huge numbers on the surface of the glacier as the sun sets. Under cover of darkness they gorge themselves on algal scum, wind-blown pollen, and other digestible motes of organic matter, only to bore back into the ice - up to six feet down - as the sun begins to rise next morning. They appear to be positively allergic to sunlight and rather skittish at any sign of movement or passing shadows when emerging.1 Researchers believe they may live for up to ten years.2
First found in 1887 on the Muir Glacier in Alaska, these endearing little chaps have even inspired verses (in which much poetic license is taken with respect to fact) by Robert Service entitled, "The Ballad of the Ice Worm Cocktail". Here are a few lines for your delectation:
Yet all is clear as you draw near - for coyly peeking out
Are hosts and hosts of tiny worms, each indigo of snout
And as no nourishment they find, to keep themselves alive
They masticate each other's tails, till just the tough survive.
Although their life cycle remains a mystery, with no egg cocoons yet being found, scientists are learning much about these miniature strands of spaghetti. The two most obvious features of interest about these worms are how they avoid freezing at such low temperatures (even NASA has been studying them in hopes of learning how they pull off this trick) and how they wriggle through the ice as effortlessly as their cousins tunnel through soil.
When it comes to cold resistance, iceworms reverse normal behavior and become more active as the temperature drops until freezing point is reached. Researchers have found that these worms have higher levels of certain life chemicals (ADP, ATP, and AMP) than other creatures3, but turning that bare knowledge into an explanation remains elusive. The worms neither have the antifreeze in their blood that enables some Antarctic fish to function in near-freezing water nor can they generate their own heat like polar bears do. Scientists are also puzzled by a paradox. Iceworms freeze solid and die at temperatures much below freezing while tardigrades, which cannot function at freezing point, are nevertheless able to survive in suspended animation at much lower temperatures.
As for their mining ability, well, nobody knows how they do it. They do appear to be stopped in their tracks by some layers of ice, being occasionally found in large concentrations at a transition zone, but the nature of the properties that facilitate and impede burrowing are unknown. Some iceworm aficionados believe they use tiny cracks in the ice to move around. Microscopic studies of the worms show that they have a larger pore on the head than "ordinary" worms, leading some researchers to speculate it may aid burrowing "by depositing substances that melt ice."4 enabling the worm to move through it like a warm knife through butter.
Shsh! Listen carefully. Can you hear it? Heaven chuckling. And did you hear that voice, too? Unless I'm mistaken, it said, "You would never have dreamed that one up, would you?" Ah, Lord, is there anything You haven't thought of?
1Daniel Shain and others 2001, Distribution and behavior of ice worms (Mesenchytraeus solifugus) in south-central Alaska, Canadian Journal of Zoology, 79:1813-1821
3Napolitano and others 2004, The ice worm, Mesenchytraeus solifugus, elevates adenylate levels at low physiological temperature, Comparative Biochemistry and Physiology Part A, 137:227-253
4Daniel Shain and others 2000, Morphologic Characterization of the Ice Worm Mesenchytraeus solifugus, Journal of Morphology, 246:192-197