Life in nature's deep freeze
By Jack Souther,
"Their bellies were a bilious blue, their eyes a bulbous red.
Their backs were grey, and gross were they, and hideous of head.
And when with gusto and a fork the barman speared one out.
It must have gone four inches from its tail-tip to its snout."
From "The Ballad of the Ice-worm Cocktail", by Robert Service.
In fact there really are living, wiggling ice worms but they bear little resemblance to the creatures concocted from spaghetti and ink by Service's barroom buddies for the sole purpose of grossing out the tourists. Thread-like and only a couple centimetres long the real things are much too small to spear and they have no visible eyes. But despite their modest physical stature science has provided them a taxonomic spot among the annelids and bestowed on them the apt and impressive title " Mesenchytraeus solifugus " or, the "worm that flees the sun".
Ice worms are dark-pigmented oligochaete worms, a class which includes the common earthworm. They are found in the temperate glaciers of the Pacific Northwest, Greenland and the U.S.S.R. where they live in the interconnected channels in granular snow and between the crystals of glacier ice. Unable to survive outside a tiny temperature range they are surprisingly not resistant to freezing. Although they can survive cooling to minus 7 C they are vulnerable to temperatures above 7 C and will die if touched.
Although most ice worms live in the upper few centimetres of glaciers they have been found as deep as two metres below the ice surface. At that depth most temperate glaciers are nearly isothermal with constant temperatures hovering around the freezing point. The worms have clearly evolved to fill this special niche and in winter, protected by an insulating blanket of snow, they are able to migrate vertically into a temperature zone near freezing that suits their lifestyle.
To avoid the daytime sun, ice worms burrow into the ice or crystalline snow during the day and rise to the surface at dusk, when several hundred may occupy every square metre of ice surface. Manoeuvring with the aid of tiny bristles called setae, they feed on wind-blown pollen, fern spores, and red snow algae.
According to Daniel Shain, an evolutionary biologist at Rutgers University and one of the few scientists who has studied ice worms, very little is known about their subsurface lives. They are one of the few animals that complete their life cycle, from egg to adult, at 0 degrees where the cellular and metabolic processes of most living things cease. Kept in water near the freezing point an ice worm can survive up to two years without food.
Their close relatives, the giant tube worms that live in the boiling volcanic vents of the deep ocean, on the other edge of life's temperature envelope, are known to live up to 200 years and Shain speculates that ice worms may be similarly long-lived. He also believes that studying their unique physiology has implications for both doctors and astronauts. They may provide clues on how to prolong the life of human organs prior to transplant and how to keep a person in a state of suspended animation for space travel. Clearly Robert Service is not the only one whose imagination has been piqued by the lowly ice worm.
Saturday, June 8 Pemberton Bird Walk at One-Mile Lake, 8 a.m. Mark this great event on your calendar last year we saw almost 50 species of birds (and lots of interesting flowers) in two hours! The walk leaders are the five crack birders from the annual Breeding Bird Survey. Meet in the parking lot. Call Bob Brett (604-932-8900) for details.
Saturday, June 8 Breeding Bird Slide Show, 7 p.m. The five expert and very funny birders here for the 27th annual Breeding Bird Survey will tell us what its all about. Everyone is welcome to join us for this event at the Tantalus Lodge conference room .refreshments served. Call Bob Brett (604-932-8900) for details.
Sunday, June 9 Squamish Estuary Bird Count, 7 a.m. Meet at the Howe Sound Inn & Brew Pub in Squamish. All levels of birders are welcome on this half-day event sponsored by the Squamish Estuary Conservation Society.
Wednesday, June 12, 6:30 p.m. Nature Walk at Nairn Falls . Meet at Whistler Secondary School at 6:30 p.m. for a convoy north and a walk in to Nairn Falls. Themes include fluvial processes and landscapes when water meets rock. Call Mitch Sulkers (604-932-3707) for details.
Sightings and Memberships: NatureSpeak is prepared by the Whistler Naturalists. To become a member or to report noteworthy sightings of mammals, birds, or other species, contact Lee Edwards (905-6448; e-mail: firstname.lastname@example.org).