Animal Navigation
Six-week
investigative seminar: Each session included both a lecture and
group laboratory work.
Week 1:
The students were given a brief introduction to the sensory and motor
systems of terrestrial insects and marine crustaceans, including both
structure and function. Students dissected crayfishes in pairs for the
rest of the laboratory period, and learned fundamental concepts such
as 1) animal anatomy and anatomy descriptors (anterior, posterior, etc),
2) segmentation, 3) open versus closed circulatory systems, 4) sensory
appendages (structure and function), 4) the role of adaptation in animal
design.
Week 2:
Students were given a mini-ecology and min-oceanography lecture to place
these animals into their environmental context. Students then
used this information to predict and learn about the ecological adaptations
of these animals to their different environments. The laboratory exercise
involved behavioral observation of living crayfishes and their responses
to different sensory stimuli (light, smell, taste, touch, vibration).
Students also learned the basics of behavioral observation, scoring
behaviors, timing behaviors, and organizing and keeping a proper scientific
notebook for observations.
Week 3:
In week 3, students were given pairs of crayfish to observe, time, and
score behavioral interactions between the two animals (“boxing matches”).
Groups of 4 students, each with assigned roles (Observer 1, Observer2,
Timer, Scribe), watched and scored each boxing match between 2 crayfish.
Crayfish fighting behavior is somewhat ritualized, and the behaviors
are obvious and straightforward to score. After each “match”, a
winner and loser were declared (the “loser” will back away from
the “winner” constantly until they are separated) and the duration
of the entire match was recorded. After a 5 minute rest period, crayfishes
fought again, with the students switching roles in the experiment. At
least 4 matches per group were performed and scored. Here students learn
the importance of 1) accurate timing, 2) multiple observers, 3) scoring
behavior accurately, and 4) replicability.
Week 4:
During week 4, students learned how to plot the data they collected
in Week 3. Students first graphed behaviors versus time (fight-intensity
profile), then overall fight duration versus level of intensity, to
show that crayfishes that are evenly matched usually have longer, more
intense fights as the animals determine their dominance structure. Short
fights are usually between mismatched animals---one wins quickly, and
intensity does not escalate. This is actually an introduction to ritualized
behavior and game theory, without the students realizing it at first.
Students also observed and recorded the behavior of crayfish orienting
in a simple maze. They used their newfound expertise in scoring behavior
over time to determine what behaviors are associated with exploration
(antennal touches, body touches, walking speed, etc). Students come
to realize that animals that do not rely heavily on visual information
are still quite adept at learning about conspecifics and their environment.
They were then asked to generate hypotheses and propose new experiments
to test these animals in future laboratories.
Week 5:
Student experiments.
Week 6: Student presentations. For the final meeting, Prof Basil demonstrated biomimetics with robots equipped with “virtual antennae” to replicate how freshwater crayfishes actively use their antennae to extract tactile information from their environment and make orientation decisions. They learned that the “robocrayfish” can be used to test hypotheses about orientation algorithms --- what kind of information is sufficient to make accurate orientation decisions?