After using the winghead bioenergetics simulation, students should be
able to use modeling to analyze, compare, and predict the following:
• Variation within populations. By changing cephalofoil size
(morphology) and swimming speed (behavior), individuals vary
within the population. Each variant incurs different energy expenditures and gains.
• Inheritance. Sharks in this model have the potential to reproduce if energy gains exceed energy expenditures. The successful
parental phenotype will be inherited by its offspring.
• Natural selection. Not all individuals survive, and those that do
will have differential reproductive success reflective of the number of pups birthed. Traits are passed on in unequal rates, and
this is a nonrandom process. Individuals that maximize energy
gain to energy loss in their environment, in terms of prey detection and drag, will have the highest reproduction. The phenotype with the greatest reproductive success will be the most
common in the population.
Student Reasoning While Using
Computer simulations are often complex and need scaffolding to
enhance student reasoning (Löhner et al., 2005; Sins et al., 2005).
To guide student reasoning, Sins et al. (2005) outlined five steps in
the process: analyze, use inductive reasoning, quantify, explain, and eval-
uate. The hammerhead model was intentionally made to be simplistic,
in terms of only manipulating rostrum size and swimming speed, to
reduce confounding variables and enhance student comprehension
of the most essential concepts while exploring opposing evolutionary
constraints. When using this shark model, instructors should guide
students how to deconstruct the model into its individual variables
of rostrum size, swimming speed, prey detection, energy gained,
energy spent, and pups birthed. Then students should hypothesize
how those variables interact and ultimately dictate energy budgets
for growth and reproduction. As students manipulate the model var-
iables, they will see quantitatively how each parameter changes. From
those data, they should explain how phenotypic variation affects the
opposing constraints of prey detection and drag, especially the upper
and lower limits of each. Moreover, they should connect how all of the
model variables are related and drive differential reproduction, which
is central to natural selection. Finally, students should extrapolate the
model results and apply them to concepts of natural selection, includ-
ing comparing the model results to observed results in nature and
applying them to other organisms and systems. Ultimately, these align
with the AAAS (2011) core concepts of evolution and structure and
function and the core competency of ability to use quantitative reasoning.
Furthermore, the use of this model could be assessed as skills-based
learning, meeting the core competency of ability to use modeling and
This model has been used during five separate terms, to date, in a college course that was recently revised with funding by the National Science Foundation. Students in this class also used other evolutionary
models. On two separate occasions, the overall course was independently assessed per National Science Foundation mandate. When
compared to the commercial models, ~75% of the students ranked
this shark model as of similar quality. Anonymous student comments
about the shark model were overwhelmingly favorable and complimented the model’s ability to reinforce concepts of natural selection.
While the model I produced is free to use and distribute, instructors
may wish to build their own. To do so, at minimum a similar model
must contain applications of Equation 1, Equation 2, and simulated
prey detection and capture. Fish bioenergetics is an extensive field,
and data are widely available. Jørgensen et al. (2016) provide a contextual overview.
This material is based on work supported by the National Science
Foundation under grant no. NSF DUE-IUSE 1504662. Any opinions, findings, and conclusions or recommendations expressed in
this material are those of the author and do not necessarily reflect
the views of the National Science Foundation.
AAAS (2011). Vision and Change in Undergraduate Biology Education:
A Call to Action. http://www.visionandchange.org.
Alters, B.J. & Nelson, C.E. (2002). Perspective: teaching evolution in higher
education. International Journal of Organic Evolution, 56, 1891–1901.
Anderson, D.L., Fisher, K.M. & Norman, G.J. (2002). Development and
evaluation of the conceptual inventory of natural selection. Journal of
Research in Science Teaching, 39, 952–978.
Barousee, J. (2009). Hydrodynamic functions of the wing-shaped heads of
hammerhead sharks. M.S. thesis, Florida Atlantic University, Boca Raton.
Bouyoucos, I.A., Montgomery, D. W., Brownscombe, J. W., Cooke, S.J., Suski, C.D.,
Mandelman, J. W. & Brooks, E.J. (2017). Swimming speeds and metabolic
rates of semi-captive juvenile lemon sharks (Negaprion brevirostris, Poey)
Figure 3. An optional graph builder (third tab) that instructors
may assign when students use the model.