Thursday, November 4, 2010

The Saaaands are Alive with The Sound of Muuuuusic!

This post reminds me of that lovely Julie Andrews song, parodied here.

Dear Readers (How are you?),
I confess: I've been pretty biased against sand.  Hydrologically speaking (which is totally my paradigm), I consider it the boring soil texture of the three (sand, silt, clay).  Por ejemplo:
  • Water flows through it the easiest (of sand, silt and clay), meaning is has the highest hydraulic conductivity*, and 
  • it holds onto the fewest nutrients because of it's low cation exchange capacity* (I mention CEC here and here).  
  • Also, it's soil moisture curve* leaves much to be desired.  I mean look,

(image source, from an awesome looking lecture on soil water relationships in soil)

Just look at how quickly sand loses it's soil moisture when the water table drops (shown on the x-axis).  Yawn, right? Clay holds onto it's water!! Jeez.

But recently, I came to terms with the idea that maybe sand was more interesting than I thought.  A few weekends ago, we saw some familia in Corpus Christi, TX and went to Padre Island National Seashore (Click here for map). As in, we went to the beach, where you get to play in nothing but pure, boring, bland sand.  So you'd think I'd be bored out of my mind there, but lo, it was not true.

Mi familia y yo started digging in the sand of the intertidal zone, and did some learning (BTW,  sandcastles, sand-chairs, and drip mountains are totally learning.)

This is South Padre Island National Seashore's intertidal (IT) zone*.  The IT zone here would be everything in between the seaweed piles to the low tide waves.  An IT ecology lesson here.
Wanna know what we saw?  Aliens!  Just kidding: one long, skinny worm, tonsa things that looked like dark, stubby worms, a decapod (a ten-footed something-or-other, shrimp?), and something that looked like a "sand crab" to my untrained eye.  Kinda like everything on this marine science page (seriously, look at the cool pictures!).
This is a blood worm (genus Euzonus), which might be what I saw (Image credit).
So, in conclusion, the sand is alive!   These creatures have ecological importance as nutrient recyclers, just like our soil brethren.  For example, can you believe, and I quote:
Some worms called polychaetes [my note: this is a class of worms that inlcude the Euzonus genus] simply eat the sand whole and let their digestive systems clean it off. Out the back end, eventually, comes a trail of clean sand (source).
Blood worms function on the sandy beach much like the earth worms do on land — they ingest the sediments (sand for the blood worms) and digest the organic material found between the sand grains. This type of feeding is called deposit feeding and results in a type of "cleaning" of the sediments. (source
You mean they poo a trail of clean sand!?!? Awesome.  So, why are we thankful for tiny sand creatures?  They don't cause diseases and they clean up after our organic mess.  HUGS YOU, little sand creatures!!!

And to you, Sand: I'm sorry for thinking you were boring.  I love your interstitial fauna* and you are easier to wash off our hands than clay.  Thank you, too :-)

It turns out that sand is waaaaay more interesting than I thought.  Check out this book review blog post by Brian Romans on the book Sand by Michale Wellans.  This author also has a SAND BLOG on all things sand!  Now back to your regular programming...

Intertidal zone: The transitional coastal region located between high and low tide marks (source).
Hydraulic conductivity: "A measure of the capacity for a rock or soil to transmit water; generally has the units of feet/day or cm/sec (source)," or "The ease of movement of water through the soil relative to a potential gradient (source)." Think of a potential gradient as a difference in water table levels: water flows from high to low water table levels.
Cation Exchange Capacity: "a measure of the negative charge on soils (primarily on clays and organic matter). It is expressed as the quantity of cations (positive ions) that can be adsorbed by the soil (source)."
Soil moisture curve: a graph that shows the relationship between soil moisture content and pressure head (aka water table draw-down).
Interstitial fauna (meiofauna): the tiny animals that live in between the sand grains.  Also "loosely defined as animals capable of passing through a 0.5-mm mesh (source)"


  1. I never knew sand and its inhabitants were so interesting! Thanks for the exposé!

  2. Thanks! Be sure to read the pages that I linked for some real amazing-ness. The Sand book sounds quite poetic. I love artfully written science lessons.

  3. We use bloodworms as bait for fishing here on the East coast. Most of them come from the low water marshes in New Jersey. Like your blog.

  4. Anonymous, thanks for liking my blog. I like your comment! It makes a lot of sense to do that. I bet it is fun to look for them...

  5. Thanks, Micadart! Good point with the colors. I'll keep it for now since soil is dark (and you know, brown) and that is the mood I am going for.. dirty ;-) Thanks for the visit!