I have been posting mostly math-based Scratch projects so this is the first of several science-based Scratch projects that I will be posting in the near future.
You may well think the simple movement strategy of
moving forward until an object is struck, backing up a short distance, turning
left or right through a small angle, and then moving forward again, is too
simple to be of much use. But in nature, exactly this behavior can be found in
simple organisms like the single-celled paramecium. This mode of motion is
called kinesis kinesis (a movement that is a response to a stimulus but is not
oriented with respect to the source of stimulation).
Small hairs called cilia cover the outer body of a paramecium. These
hairs act like tiny oars to propel the organism through water and also help the
organism gather food.
When a paramecium strikes an object in its environment, the cilia
reverse direction moving the paramecium backwards. The organism then turns left or right through a small angle,
and moves forward. By continually repeating this process the paramecium is able
to move around obstacles in it path.
In this Scratch simulation, the paramecium is swimming though a thin layer of water containing
a grain of sand. The sprite 1 script models kinesis.
I have on my ‘to do’ list to model a euglena that propels itself
with a single, long cilia and an amoeba that 'flows' pseudopodia (false feet) to
move.
http://scratch.mit.edu/projects/10443264/