Wednesday, April 16, 2014
By Rachel Ohm
UNITY — In the woods of Unity College, students hunt for a tiny eight-legged animal that is capable of surviving in extreme environments, from outer space to the bottom of lakes and oceans to the peaks of the Himalayan mountains.
This tardigrade, seen Thursday at Unity College, is equipped with an armor shell and green tint from its herbivore diet.
Photos by Michael G. Seamans/Morning Sentinel
Ben Sawtelle, 19, a freshman at Unity College, scrapes samples of moss and lichens from a dead tree in search of tardigrades.
Tardigrades, also known as water bears or moss piglets, are among the world’s smallest animals. Their discovery in North America dates to the 1873 findings of a priest in the town of New Gloucester. For years, there were no further scientific studies of tardigrades in Maine until their recent rediscovery sparked an interest at Unity College, an environmentally focused liberal arts school with an undergraduate population of about 550 students.
On a recent snowy day, a group of students working with Emma Creaser, a professor of marine biology, poked through lichen, moss and leaf debris looking for tardigrades, which are compared to bears or piglets because they have stout legs and rotund bodies.
Humans can’t see tardigrades. At an average size of two-tenths of a millimeter, they are not visible to the naked eye, yet their ability to withstand extreme environments means they are capable of doing things that humans can’t. In 2007, tardigrades were the first animals to survive exposure in outer space, and the study of them has attracted scientists interested in unlocking the key to living forever, thanks to their ability to preserve their bodies for extended periods of time without food, water or oxygen.
Studies so far have shown that they are capable of living up to 10 years in a hibernationlike state called cryptobiosis, only to be revived with a single drop of water.
“They’re sort of everywhere, but they inhabit a microcosm that we don’t even know about,” Creaser said as she led the students through the woods, making notes of which trees they are collecting samples from.
Even though it is the middle of winter and 6 inches of newly fallen snow blankets the ground, the animals still can be found on moss and lichens, where they inhabit layers of water surrounding the plant. Little is known about tardigrades, but because scientists know the habitat they prefer, material can be gathered that probably will contain the animals, Creaser told the students as they collected the samples in brown paper bags.
Tardigrades are some of the smallest animals known to man. They’re classified as animals because they move, eat plants and animals, have the ability to reproduce either sexually or asexually, and have a nervous system and brain.
More than 1,000 species of tardigrades have been documented worldwide since their discovery in the late 1700s. Their discovery in North America is credited to a Maine priest, W.R. Cross, whose findings were documented in a December 1973 publication of The American Naturalist.
“It is white, about 14/1000 inch long, and has minute eyes composed of about ten irregular facets” is the way the animal is described in the journal, along with a drawing showing its eight legs, each with a set of four claws.
For decades, no one in Maine studied tardigrades – until 2011, when Harry Meyer, a scientist visiting Maine, wrote a research paper on samples he found in Bar Harbor.
The paper caught the attention of Creaser, who has since documented 11 species of the animal throughout the state, including two never-before-discovered species in Rangeley and Hancock. Last summer, they were documented in Acadia National Park. Creaser is working on a grant to study whether they can be found off the coast of Maine.
Her students are also excited about the project.
Ashleigh Munton, 20, a junior majoring in marine biology and secondary education, discovered a tardigrade by accident while looking at a slide of water from a mud puddle in a biology class.
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click image to enlarge
Unity College professor Emma Creaser peers through a microscope at a tardigrade as student Ben Sawtelle watches.