Examining Fish Morphological Variation between Differing
Stream Flow Rates
[ Sara Entrekin ]
Abstract
The shape of an animal’s body can be an adaptation for overcoming specific
environmental challenges. For example, fish that live in fast-flowing riffles must face
immense turbulence compared to fish living in slower-moving water. The body
shape of a fish influences its ability to be hydrodynamic and efficiently move in
these different environments. We collected fish from pools and riffles in Clark Creek
and measured their depth to length ration to test the prediction that the depth to
length ratio of fish from pool habitats would be significantly greater than the depth
to length ratio of riffle fish. Results from our group showed that poll fish have a
[significantly] [greater] mean, which [supported] our prediction. Overall [ 8 out
of 12] groups found a significant difference between pool fish and riffle fish,
[strengthening] support for our prediction.
Introduction
Natural selection frequently shapes the body plan of animals. This is particularly
apparent when considering the variation of overall body shape across diverse fish
lineages. Some fish, such as minnows have long, slender bodies, whereas other fish,
such as sunfish, have proportionally taller, less lengthy bodies.
, Differences in proportion can affect how quickly a fish can move or maneuver in
water flowing at different speeds; a tall fish is subjected to much more resistance
and turbulence in fast-flowing water, whereas in slow-moving or stagnant water the
added height allows it to turn more rapidly than a narrow fish (Ensign 2013).
We hypothesize that fish in fast-moving riffles will have longer more slender bodies
compared to fish collected from slow-moving pools, because this allows riffle fish to
more easily overcome the increased resistance and turbulence when swimming in
riffles.
If riffle fish are longer and narrower than pool fish, then we predict that the mean
depth to length ratio of riffle fishes will be smaller than the mean depth to length
ratio of pool fish. To test this prediction, we performed t-tests on depth to length
measurements of fish from both habitat types in Clark Creek (Bartow Co.).
Materials & Methods
Prior to the lab, a large sample of fish was collected from riffle habitats separately
from an approximately equal sample from pool habitats.
Each pair of students randomly chose 8 fish from the pool sample and 8 fish from
the riffle sample and measured their length from mid-mouth to the proximal edge of
the tailfin and depth from the base of the dorsal fin to the ventral edge of the fish at
the approximate midpoint of the fish’s length as described in the lab protocol
(Ensign 2013).
Stream Flow Rates
[ Sara Entrekin ]
Abstract
The shape of an animal’s body can be an adaptation for overcoming specific
environmental challenges. For example, fish that live in fast-flowing riffles must face
immense turbulence compared to fish living in slower-moving water. The body
shape of a fish influences its ability to be hydrodynamic and efficiently move in
these different environments. We collected fish from pools and riffles in Clark Creek
and measured their depth to length ration to test the prediction that the depth to
length ratio of fish from pool habitats would be significantly greater than the depth
to length ratio of riffle fish. Results from our group showed that poll fish have a
[significantly] [greater] mean, which [supported] our prediction. Overall [ 8 out
of 12] groups found a significant difference between pool fish and riffle fish,
[strengthening] support for our prediction.
Introduction
Natural selection frequently shapes the body plan of animals. This is particularly
apparent when considering the variation of overall body shape across diverse fish
lineages. Some fish, such as minnows have long, slender bodies, whereas other fish,
such as sunfish, have proportionally taller, less lengthy bodies.
, Differences in proportion can affect how quickly a fish can move or maneuver in
water flowing at different speeds; a tall fish is subjected to much more resistance
and turbulence in fast-flowing water, whereas in slow-moving or stagnant water the
added height allows it to turn more rapidly than a narrow fish (Ensign 2013).
We hypothesize that fish in fast-moving riffles will have longer more slender bodies
compared to fish collected from slow-moving pools, because this allows riffle fish to
more easily overcome the increased resistance and turbulence when swimming in
riffles.
If riffle fish are longer and narrower than pool fish, then we predict that the mean
depth to length ratio of riffle fishes will be smaller than the mean depth to length
ratio of pool fish. To test this prediction, we performed t-tests on depth to length
measurements of fish from both habitat types in Clark Creek (Bartow Co.).
Materials & Methods
Prior to the lab, a large sample of fish was collected from riffle habitats separately
from an approximately equal sample from pool habitats.
Each pair of students randomly chose 8 fish from the pool sample and 8 fish from
the riffle sample and measured their length from mid-mouth to the proximal edge of
the tailfin and depth from the base of the dorsal fin to the ventral edge of the fish at
the approximate midpoint of the fish’s length as described in the lab protocol
(Ensign 2013).
