Year
of arrival 1992.
Professor, tenured. B.A., Zoology,
The
overall goal of my research is to test hypotheses about the relationships
between morphology, function, and ecology in an evolutionary framework by
adapting techniques from comparative functional morphology and biomechanics. My
primary focus is on planktivorous fish that filter
enormous volumes of water to retain food particles that are too small (~ 5 µm
to 2 mm) to be sensed and engulfed individually. These filter-feeding fishes
(e.g., anchovies, herring, and tilapia) belong to twelve orders and comprise at
least 25% of the world fish catch. Although they have substantial impacts on
plankton abundance and community structure, the methods that they use to
extract small food particles from the water are unknown. By inserting a
miniature fiberoptic endoscope and a thermistor flow
probe into the mouths of freely-swimming fishes in the laboratory, I can
visualize and measure flow near the gill rakers where
particles have been assumed to be captured. The unexpected flow patterns
recorded recently in three distantly-related filter-feeding fish species
indicate that the rakers function as a crossflow filter. Although crossflow
filtration is a multi-billion dollar industry for the manufacture of products
that we use every day (e.g., dairy products, wine and beer, pharmaceuticals),
this filtration mechanism had not been recognized previously in any
vertebrate. The techniques used in my laboratory
for flow visualization and measurement can be adapted to study the function of
internal feeding structures in a diversity of animals, including filter-feeding
birds and bivalves. My research program is expanding to include the study of mouthbrooding and larval feeding/locomotion in filter-feeding
fishes.
Potential
research projects include studies of fish feeding ecology and behavior, the
design of physical models for food particle encounter and retention, and
electron microscopy of oral structures.
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updated 01/17/19
College of William and Mary, Department of Biology
slsand@wm.edu