CONTROLLING
THE ANIMATION:
Wait for the animation to load
completely and play through once. To stop the animation, click on the
"pause" button. To see the frame that precedes the paused frame, press
the "previous" button. To see the frame that follows the paused frame,
click on the "next" button. To resume the animation, click on the
"play" button.
PROCEDURE:
1) Lay a small clear transparency sheet over the animation. Use two small
pieces of paper tape to secure corners of the transparency sheet to the monitor
screen. Use a marking pen to make a series of dots on the sheet that track the
frame-by-frame position (starting at the frame labeled 0/30) of the worm's head end (top) as it
swims through vinegar. [NOTE: Each frame of motion represents 1/30th
second of elapsed time (0/30, 1/30, 2/30 etc)]. Make sure the correct elapsed
time is recorded for each dot and make sure the distance scale is carefully
recorded on the transparency sheet.
2) Remove the transparency sheet and lay it on a piece of white paper.
Then, estimate the forward velocity of swimming, as determined by
computing the worm's forward progress during a 5/30 sec interval (=1/6 sec).
Express units in mm/sec. Compare your velocity values to those seen in a
leech
or
blackworm.
3) Attach a second transparency sheet over the animation so that the
animation window is near the left edge of the sheet. Advance the animation to frame 0 and
make a tracing of the worm's overall body shape. Label the tracing
"0/30". Next, advance the animation to the next frame and shift the
position of the transparency sheet about 2 cm to the left. Make another tracing
of the worm's body shape and label it "1/30". Repeat this procedure
until you have a series of at least six consecutive tracings, with the first image at the
left and the last at the
right.
4) The traced images should show that the worm's forward locomotion
consists of undulatory, rhythmic waves. Describe the shape
of these waves. In what direction do the waves move along the body?
5) Use the tracings you just made to estimate wave frequency.
This is done by determining the time interval (in sec) it takes to complete one full
cycle of wave motion. Then, take the reciprocal of this value to obtain wave frequency,
expressed in cycles/sec.
Click
here to see non-interactive GIF animation
Software for controlling interactive animations was
developed by TOM DREWES
