Razor Clam's Rapid Burrowing Technique Involves Turning Soil Into Quicksand
Posted on May 27, 2012
Amos Winter from the Massachusetts Institute of Technology has been studying the Atlantic Razor clam to develop ideas for building self-burying robots. Winter calls the Razor clam the "Ferrari of underwater diggers." The Razor clam can dig at a rate of about a centimeter per second. Winter determined that the Razor clam cannot be burying itself solely by using its muscular foot. The foot alone would not be strong enough for the clam's rapid burying technique.
Winter built a transparent environment for the clam so he could study its movement. He determined that the clam quickly buries itself essentially by temporarily turning the sand around its muscular foot into quicksand. The clam extends its foot into the sand a little ways and then inflates it (fills it with blood) to anchor it in place. The clam then contracts it shell which pulls some liquid in toward its body enabling it to pull itself down farther into the sand. The clam repeats this process to dig itself deeper into the sand.
Winter says, "As soon as it starts contracting the shell it relieves the pressure it is exerting on the soil and that sucks more water towards its body so that you get increased unpacking of the soil particles."
This quicksand technique allows the clam to reduce drag and conserve burrowing energy as it is much easier to dig into quicksand than dry packed sand.
Here a couple videos of Razor clams in action. Take a look:
The research was published here in The Journal of Experimental Biology.