Research

Linking Sensory Biology and Biomechanics

We study how fish sense water flow and how fish swim

Fish sense water flow with their lateral line systems. This unique sensory system is distributed on the head and along the length of the body and several lateral line patterns are found among fishes. The sensory unit of the lateral line system is called a neuromast, which are located on the skin or in pored canals. Each neuromast is made up of clumps of hair cells and the hair cells are stimulated by water flow. The lateral line system contributes to many behaviors including prey detection, schooling, swimming, communication, and predator avoidance.

The lateral line system of the silver hatchetfish.

How does lateral line structure relate to its function?

There are 34,000+ species of fish and many different lateral line patterns are found among fishes.

We study how morphological and behavioral adaptations are linked to lateral line function.

Current projects include:

How does vision and the lateral line system contribute to fish swimming in turbulence?

By designing experiments that combine sensory biology and biomechanics, we can understand how animals integrate information about their surroundings and apply it to their movements.

We are studying how bluegill sunfish, Lepomis macrochirus, swim in horizontal vortices and what role vision and the lateral line contribute to their stability in this unsteady flow. This work is done in collaboration with the Tytell Lab at Tufts University.

Bluegill sunfish have a common lateral line pattern and are known to use their lateral lines in several behaviors.

Here, we study how their visual and lateral line systems contribute to swimming in unsteady flows and if disabling one or both of these systems influences their swimming kinematics.

How can fluorescent staining aid in the exploration of lateral line diversity?

The lateral line system is not always apparent on a fish's body. Using fluorescent tools, the distribution of neuromasts on the body can be quickly viewed and quantified. We aim to use these methods to explore lateral line patterns in local Illinois fish and beyond.

For example, we investigated the lateral line system of the giant danio, Devario aequipinnatus. Below are images of the same fish under a dissection microscope under LED illumination (left) and under fluorescence (right). Prior to the fluorescence staining, we did not know this species had so many superficial neuromasts on its cranium.

Adult giant danio under LED illumination.

Adult giant danio under fluorescence illumination. Fish was stained with 4-di-2-ASP for 5 minutes.

Please see this paper (Mekdara et al., 2018, JEB) for how giant danios use their lateral lines while schooling.

Fluorescent staining can be used to compare closely related species.

This image is of the lower jaws of two closely related Lake Malawi cichlids, Tramitichromis sp. (left) and Aulonocara stuartgranti (right). While both species have similar numbers of neuromasts and in the same general location on their bodies, the size and shape of the neuromasts are different.

(Figure modified from Schwalbe and Webb, 2014, Zoology).

Does the lateral line filter out self-generated flows?

In the environment, fish need to sense and decipher complex flows and compensate for self-generated signals. Fish generate flow around their bodies while swimming from the movement of their fins and body and these flows are detected by the lateral line system. Yet, fish are able to detect important stimuli (prey, neighbor, predator) over this self-generated flow. How are they able to do this?

Using electrophysiological techniques, we aim to study the mechanisms that allow the lateral line system to filter out this hydrodynamic noise. We aim to provide novel insights into how the lateral line achieves its sensitivity. This research also has implications for human health, since the auditory and vestibular systems also contain hair cells like those in the fish lateral line system.

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