Creating the Ultimate Model Lizard
Students Research Animal Behavior on Spring Term Trip to Jamaica
When you hear Jamaica, what do you think? White sandy beaches? Warm weather? Lizards?
Most people don’t necessarily associate lizards with Jamaica.
Nonetheless, biology Professor Dave Clark and 12 Alma College students
traveled more than 1,500 miles to study lizards during the May 2008
spring term.
But they learned about more than biology. Clark and his students
learned about new uses for computer technology, robotics and how music
technology can be used to study the lizards’ territory habits.
Dave Clark and his model lizard.
Lizards communicate using a pattern of head bobs and opening
their dewlaps — a colored flap of flesh underneath the chin that
lizards can fan out and retract as needed.
To study the patterns of these movements and decipher how lizards react
to certain situations — such as another lizard entering its territory —
Clark wanted to build a 3-D model of a lizard.
Plaster casts of the animals were constructed and latex rubber molds of
the lizards were produced. These rubber casts were stretched over a
metal frame that was operated by a pair of small radio-controlled
servomotors.
But he still needed a way to operate the head bobs and dewlap openings.
Enter music technology called MIDI — short for musical instrument
digital interface. MIDI is the technology that allows computers,
electronic instruments and other devices to communicate to one another.
Clark first learned about MIDI technology after participating in a
computer technology workshop taught by Alma College Music Professor Ray
Riley.
Riley demonstrated how MIDI technology could be used to control musical
instruments, and Clark discovered that the same technology could be
used to control servomotors used to operate animatronics and other
special effects in Hollywood.
Clark and Riley worked together to program certain combinations of head bobs and dewlap openings in Clark’s lizard model.
“As scientists, we don’t operate in a vacuum, and this is a wonderful
example of the kind of collaboration and interdisciplinary sharing of
ideas that can occur at a liberal arts college like Alma,” says Clark.
Each lizard species has a “signature display,” which broadcasts
territory to the other males in the area and is also used for mating.
There is also a “challenge display” used when confronting other males.
Males use these displays to indicate their position in their territory,
their status and their readiness to mate with a female. The dewlap or
“throat fan” in particular is used to attract females. The bigger and
brighter the dewlap, the better the male.
Constructing the dewlaps was a challenge, because latex versions soon
wore thin and broke. Clark spent several weeks trying to come up with
the right design and shape.
Here again, music technology saved the day as Clark discovered that a
modified guitar pick pushed and pulled by a guitar string would do the
trick quite nicely.
“I was sitting on the couch next to my daughter drawing pictures of
dewlaps to attach to the robot,” he says. “When suddenly, the
shape I came up with was that of a guitar pick. I found an old
pick in my guitar case, and it worked perfectly.”
The lizard Clark created isn’t species specific, so he programmed
different displays using MIDI. He also created different colored
dewlaps to determine whether the displays themselves or the colors of
the dewlaps were more important in communication.
Though Clark was worried about how the model would work in the field,
he said the group had great conditions — there were plenty of lizards,
and they had no problems interacting with the model.
Though all six pairs of students studied the lizards, not all of them
worked with the model. One group of students studied how the light in
lizards’ habitat can affect dewlap color; another looked at the
lizards’ reactions to a 3-D video image of another lizard.
Students also studied how lizards respond to snake predators, territory
size and activity patterns of lizards and how lizards change colors.
“In addition to learning more about biology, I learned how to edit
movies, cut graphs from a journal article to use as a visual aid for a
power point,” says senior Angelica Luttrell.
The group stayed at the Discovery Bay Marine Lab, which is part of the
University of the West Indies, for two weeks conducting research.
“Few people at the undergraduate level have opportunities such as this,
and I saw it as a way to travel, learn and gain a competitive edge for
admission into graduate school,” says junior Paul Converse.
Sophomore Jeff Beck went on the trip and helped Clark research seven lizards brought back from Jamaica and 36 from Florida.
“I was interested in this trip because I am intrigued by animal
behavior,” Beck says. “But I learned an important life lesson in the
midst of conducting an experiment. After seeing the living conditions
in Jamaica, I have learned to appreciate what I have here.”
— Amanda VanLente-Hatter
Posted: Thu, August 14th, 2008 at 9:13AM
