July 22, 2010 | David F. Coppedge

Tiny Life in Extraordinary Motion

Don’t despise small things.  Miniature plants and animals can pack some amazing punch and technology, as shown in two recent findings.

  1. Plant explosion:  Peat moss.  That’s the filler in our indoor plant soil and Live Science reported that its pots shoot its spores out at 89 miles per hour, producing accelerations of 36,000 G’s.  Some spore clouds reach 80 times the height of the spore capsule before slowing down from air resistance.
        The tiny plant produces a vortex ring like a smoke ring, an “extremely efficient way for a material to move through space.”  Because of its success at spreading its spores, Sphagnum moss covers about 1% of earth’s land surface – an area more than twice the size of Texas.  Joan Edwards [Williams College], who along with Johan L. van Leeuwen [Pomona College] published their findings in Science, said, “Sphagnum’s body is very simple, and yet it’s doing this very complicated thing.”  Pressure builds up in the tiny capsule like a pressurized super soaker squirt gun, then pop! goes the efficiently-designed cloud of spores.  “It’s really special,” she said.  “Other mosses do exciting things, but not this exciting.”
  2. Animal tractor:  We’ve all seen caterpillars crawl, with waves of motion proceeding from back to front.  Scientists at Tufts University found something else, reported Science Daily: the insides move to a different drummer than the outsides.  “They found that the gut – essentially a tube suspended at the rear and head of the caterpillar and decoupled from the body wall – moved nearly a full step in advance of the surrounding structures,” the article said.  “In contrast, gut movement was ‘in step’ with motion of the head and rear.”
        This “crazy crawl,” Live Science said, is unlike any other motion seen in the animal kingdom: “their guts slide forward before the rest of their body does.”  It took visible and X-ray videos to see the process.  Live Science said the researchers wanted to know if this motion provides an advantage; Science Daily wondered if it provides an evolutionary advantage: “More research is needed to determine if this phenomenon gives caterpillars an evolutionary advantage, in the same way that synchronizing breathing and tissue movements benefits running vertebrates, or arm swinging by walking humans increases stability and reduces metabolic costs.”  That sentence begs the question that advantageous traits evolved.
        Regardless of how the caterpillar came up with its crazy crawl, the scientists are eager to imitate it.  They envision a new kind of soft-bodied robot that might use the same inside-first, outside last propulsion mechanism.  “Understanding this novel motion system may help efforts to design soft-bodied robots,” said Barry Trimmer of Tufts University.  It goes without saying that the tractors brand-named “Caterpillar” have not yet achieved the feat of their namesake.

For additional small wonders of propulsion, see the entries about water striders (08/07/2003), the froghopper (08/01/2003), plant drill bits (05/11/2007), maple helicopters (10/21/2009) and other “Amazing Facts” chain links.

We apologize for upsetting your digestion with the evolutionary tale.  Biologists need to understand that all advantages are not evolutionary advantages.  They might be designed advantages.  Unless they are prepared to describe in detail the sequence of inherited mistakes that led to the extraordinary functions, they should not speak in such terms.
    How many wonders remain to be found in the weeds at your feet, the insects flying in your yard, and the tiny animals in plankton at the beach, or unseen in the soil?  Get out and do a little scientific observation.  Anyone can be a citizen scientist – searching to understand the workings of the world all around us.

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