Questions that really get my brain going involve viewing and understanding dynamic and complex systems in terms of their mechanically integrated parts. That is, my research interests include comparative biomechanics, functional morphology, and ecological mechanics, particularly in aquatic organisms.

 

Mechanical tuning in fish swimming

For fish that perform bouts of continuous, often high-speed swimming by undulating a part or all of their body, there may be a strong selective pressure to reduce the energetic costs of body bending. An undulating fish can be thought of as a dynamically bending beam with the potential for mechanical tuning.

Previous work on this topic has lead to the hypothesis that fish actively alter their body stiffness such that the body’s resultant natural frequency matches their tail-beat frequency. For my dissertation research in Dr. George Lauder's lab, I am working on integrating whole-body mechanics, and the kinematics and hydrodynamics of fish undulatory swimming to start to formulate direct functional relationships between body mechanical properties and swimming mechanics.

 

Hagfish swimming

I am also returning to my hagfish roots and beginning a collaborative project with Dr. Doug Fudge and Tim Winegard (Univ. of Guelph) that examines these (truly anguilliform?) swimmers. More to follow...

 

Jet-assisted walking in lobsters

For my MSc, I studied lobster locomotion in Dr. Edwin DeMont's Comparative Biomechanics lab at St. Francis Xavier University . The American lobster (Homarus americanus) has a series of paddle-shaped appendages (the pleopods) on its abdomen that it uses to generate water currents, and I was interested in their hydrodynamics and locomotory function. 

Using a quantitative flow visualization technique (particle image velocimetry, PIV) and a mechanical lobster model to characterize pleopod-generated flows and their forces, we found that the lobster’s beating pleopods are capable of producing a strong rearward jet that could assist walking in benthic habitats.

Lim, J.L. and DeMont, M.E. (2009). Kinematics, hydrodynamics and force production of pleopods suggest jet-assisted walking in the American lobster (Homarus americanus). J. Exp. Biol. 212, 2731-2745. (PDF)

Also see an article that BBC Earth News did on this work here!

 

________________________________________________________________________________

 

The ecomechanics of hagfish slime

The summer after receiving a BSc in Marine Biology at the University of British Columbia , I worked in the UBC Biomaterials lab with Dr. Doug Fudge and Dr. John Gosline on a project on the ecological function of hagfish slime.

We tested the hypothesis that the slime acts as a defence against gill-breathing predators, as the slime’s mixture of fibrous threads and mucins could become entangled in the gills and potentially suffocate a predator. Naturally, we built a “slime-vacuum” to test this (see below).

We found that hagfish slime is capable of clogging fish gills, increasing gill resistance and slowing the flow of water through them.

Lim, J., Fudge, D. S., Levy, N. and Gosline, J. M. (2006). Hagfish slime ecomechanics: testing the gill-clogging hypothesis. J. Exp. Biol. 209, 702-710. (PDF)

 

This and some of Doug's other hagfish work also got mentioned here, in the Annals of Improbable Research (issuers of the Ig Nobel Prizes)!

And in the children's book Secret of the Suffocating Slime Trap...and More!, part of the Animal Secrets Revealed! series by Ana María Rodríguez.