Research

Broadly, I am interested in the interactions between organisms and their fluid environments. I focus on very small organisms or very small biological structures that produce very small movements in fluid, called low Reynolds number flows. These flows are intuitively very different than the large-scale flow in which humans are accustomed to living since the viscosity of the fluid (how difficult it is to shear) is relatively more important to very small organisms and structures.

Fluid dynamics of odor capture by crabs

Crab antennule showing aesthetascs

Scanning electron micrograph of antennule of a brachyuran crab (Hemigrapsus oregonensis), showing aesthetascs. Photo: L. Waldrop.

To capture odor molecules from the surrounding fluid, crabs use arrays of chemosensory hairs (aesthetascs) located on their first anteannae (antennules). Crabs flick their antennules quickly back and forth, forcing odor-laden fluid into the arrays of chemosensory hairs, where odor molecules are absorbed.

The aesthetascs in this array function to both sense odor molecules from the fluid and allow capture of discrete fluid parcels to improve odor-capture performance. Because the array operates at transitional Reynolds numbers (Re = 0.1 – 10),it is able to alternately able allow water in spaces between aesthetascs and trap samples of water within these spaces to allow more time for odor molecules to contact aesthetascs via diffusion.

I investigated the fluid dynamics of odor captures in the blue crab (Callinectes sapidus) (Waldrop, Reidenbach, Koehl submitted); how odor capture changed during ontogeny (growth and development) of the Oregon shore crab (Hemigrapsus oregonensis) (Waldrop, 2013); how a terrestrial hermit crab (Coenobita rugosus) transitioned this function to air which has very different physical properties than water (see Les Houches poster [PDF, 7.9 MB]) and how ontogenetic changes impact the ability of hermit crabs capture odors in air.

PI: Mimi Koehl

The ecology and evolution of tunicate hearts

The tunicate Ciona savignyi. Photo: L. Waldrop.

The tunicate Ciona savignyi. Photo: L. Waldrop.

Tunicates (sea squirts) have tubular hearts that pump blood throughout their bodies. These tube hearts move fluid by peristalsis-like contractions of a single layer of myocardium enclosed within a rigid outer structure (pericardium). Tunicates come in a large range of body sizes (over several orders of magnitude) and their hearts operate in reasonably large range of low to moderate Reynolds numbers (Re = 0.1 – 100). I will use experimental methods (pumping mechanism, morphometrics, experimental manipulations, and micro- particle image velocimetry) and mathematical models (Immersed Boundary Method simulations) to study the effects of ontogenetic growth and metabolic demands on heart pumping dynamics, as well as investigate the role of the pericardium and heart-beat reversal in fluid transport.

PI: Laura Miller

See my profile on ResearchGate.

Video Presentations

Preliminary work on the role of the pericardium in tunicates presented at Society for Integrative and Comparative Biology meeting 2014: Video summary.

“Tiny heart, big controversy: what is the pumping mechanism of the vertebrate embryonic heart?” Google Hangout Seminar at Univ. of Central Arkansas: Video link.

Dissertation

The Fluid Dynamics of Odor Capture by Crabs. Accepted: May 2012. Open Access! http://escholarship.org/uc/item/1b07356q

Publications 

Waldrop LD, Koehl MAR. Do terrestrial hermit crabs sniff? Air flow and odorant capture by flicking antennules. In revision at Journal of the Royal Society Interface 13(114): 20150850. Email for PDF.
** See associated press on Outreach page.**

Baird A, Waldrop LD, Miller LA. (2015) Neuromechanical pumping: boundary flexibility and traveling depolarization waves drive flow within valveless, tubular hearts. Japan Journal of Industrial and Applied Mathematics 32(3): 829-846. Email for PDF.

Waldrop LD, Miller LA. (2015) Large Amplitude, Short Wave Peristalsis and Its Implications for Transport. Biomechanics and Modeling in MechanobiologyIn press. Email for PDF.
PeerJ Preprint

Waldrop LD, Miller LA. (2015) The role of the pericardium in the valveless, tubular heart of the tunicate, Ciona savignyiJournal of Experimental Biology 218(17): 2753-2763 Email for PDF.

Waldrop LD, Reidenbach MA, Koehl MAR. (2015) Flexibility of crab chemosensory hairs enables flicking antennules to sniff. Biological Bulletin 229(2): 185-198Email for PDF.

Waldrop LD, Adolph S, Diniz Behn CG, Braley E, Drew JA, Full RJ, Gross LJ, Jungck JA, Kohler B, Prairie JC, Shtylla B, Miller LA. (2015) Using active learning to teach concepts and quantitative methods is quantitative biology. A position paper from the SICB symposium “Leading Students and Faculty to Quantitative Biology Through Active Learning”. Integrative and Comparative Biology 55(5): 933-948Email for PDF.

Waldrop LD, Miller LA. (2015) Introduction to the symposium “Leading Students and Faculty to Quantitative Biology Through Active Learning”. Integrative and Comparative Biology 55(5): 898-900In press. Email for PDF.

Waldrop LD, Hann M*, Henry A*, Kim A*, Punjabi A*, Koehl MAR. (2015) Fluid flow through the array of chemosensory hairs on the antennules as the result of flicking by the shore crab, Hemigrapsus oregonensis, during growth. Journal of the Royal Society Interface, 12: 20141077.
Preprint [PDF, 1.4 MB]
** See associated press on Outreach page.**
**See associated data set and code below.**

Waldrop LD, Nguyen Q*, Bantay R* (2014) Scaling of olfactory antennae and kinematics of antennule flicking of the terrestrial hermit crabs Coenobita rugosus and Coenobita perlatus during ontogeny. PeerJ10.7717/peerj.535
PeerJ Paper: https://peerj.com/articles/535/ **Featured article in Aug. 2014**
PeerJ Preprint: 10.7287/peerj.preprints.390v1
**See associated data sets below.**

Waldrop LD. (2013) Ontogenetic scaling of the olfactory antennae and flicking behavior of the shore crab, Hemigrapsus oregonensis. Chemical Senses 38(6): 541–550. doi: 10.1093/chemse/bjt024
Preprint [PDF, 1.4 MB]

Lohmann AC*, Evangelista DE, Waldrop LD, Mah CH, Hedrick TL. Covering ground: a look at movement patterns and random walk behavior in Aquilonastra sea stars. In revision.

Upcoming Publications

Waldrop LD+, Miller LA, Khatri S+.  A tale of two antennules: modeling odor molecule capture in marine and terrestrial crabs. To be submitted Jan 2016. (+ Equal work contribution.)

Williams M*, Waldrop LD, Battista N, Miller LA. Computational model of the circulatory system of the juvenile tunicate Ciona savignyi. In prep.

* = Undergraduate student researchers.

Public Datasets and Code

Check out my code on Github (user name: lwaldrop).

Waldrop, Lindsay. (2014): “Wind speed data for shore and forest on an island in French Polynesia.” figsharehttp://dx.doi.org/10.6084/m9.figshare.1054733

Waldrop, Lindsay; Bantay, Roxanne; Nguyen, Quang. (2014): Morphometric and Kinematics data accompanying “Scaling of olfactory antennae of the terrestrial hermit crabs Coenobita rugosus and Coenobita perlatus during ontogeny.” figshare.
http://dx.doi.org/10.6084/m9.figshare.1030320

Waldrop, Lindsay; Hann, Miranda; Henry, Amy; Kim, Agnes; Koehl, M.A.R. (2014): Hemigrapsus oregonensis antennule flicking PIV data. figshare.
http://dx.doi.org/10.6084/m9.figshare.928567

Waldrop, Lindsay; Kim, Agnes; Hann, Miranda; Henry, Amy; Punjabi, Ayesha; Koehl, M.A.R. (2014): Advection code for calculating fraction of dendrite-bearing region of chemosensory hair array during flicking. figshare.
http://dx.doi.org/10.6084/m9.figshare.935514

Presentations

Waldrop LD, Miller LA, Khatri S. A tale of two antennules: the odor-capture organs of marine and terrestrial crabs show specific adaptations to their own fluid environments.Oral presentation. Society for Integrative and Comparative Biology. Jan 2016.

Waldrop LD, Miller LA. Using a biologically relevant definition of peristalsis to determine the pumping mechanism of valveless, tubular hearts. Poster presentation. Society for Integrative and Comparative Biology. Jan 2016.

Enayet N*, Waldrop LD. Effects of the finger-like lunules of rotulid sand dollars on lift and drag in steady flow. Poster presentation. Society for Integrative and Comparative Biology. Jan 2016.

Lohmann AC*, Evangelista DE, Waldrop LD, Mah CH, Hedrick TL. Covering ground: A look at movement patterns and random walk behavior in Aquilonastra sea stars.Poster presentation. Society for Integrative and Comparative Biology. Jan 2016.

Waldrop LD, Prairie JC. Using small, interdisciplinary groups to engage students as participant-scientists in mathematical biology. In Symposium “Leading Students and Faculty to Quantitative Biology Through Active Learning” organized by L.A. Miller and L.D. Waldrop. Society for Integrative and Comparative Biology. Jan. 2015.

Waldrop LD, Miller LA. Experimental and computational evidence for a key functional role of the pericardium in the tubular hearts of tunicates. Oral Presentation. 7th Int. Conference on Biomathematics, Ecology, Education and Research. Oct. 2014.

Prairie JC, Waldrop LD. Group learning assignments in an undergraduate course on mathematical modeling in biology. Oral Presentation. 7th Int. Conference on Biomathematics, Ecology, Education and Research. Oct. 2014.

Waldrop LD. Role of the Pericardium in the Tubular Hearts of Tunicates. Society for Industrial and Applied Mathematics, Life Sciences. Aug. 2014.

Waldrop LD. and Miller, L.A. Simulations of heart-beat reversal in sessile tunicates. Oral presentation. Society for Integrative and Comparative Biology. Jan. 2014. Video summary (also see above).

Waldrop LD. Evolutionary response of the chemosensory-hair array of decapod crustaceans to terrestrialization. Poster presentation. Microscale Interactions in Aquatic Environments Conference, École de Physique des Houches, France. Mar. 2013.  Link to poster [PDF, 7.9 MB].

Waldrop LD. Fluid dynamics of antennule flicking of the terrestrial hermit crab Coenobita rugosus (Decapoda: Anomura). Oral presentation. Society for Integrative and Comparative Biology. Jan 2012.

Waldrop LD, Hann M*, Henry A*, Kim A*, Punjabi A*, Koehl MAR. Fluid dynamics of the shore crab antennule. Poster. Society for Integrative and Comparative Biology. Jan 2011.

Waldrop LD. Discrete odor sampling of the Oregon shore crab Hemigrapsus oregonensis during ontogeny. Oral presentation. Society for Integrative and Comparative Biology. Jan 2010.

Kreft JK, Waldrop LD, Koehl MAR. Low landings lead to lofty living: forces on newly settled invertebrate larvae in realistic flow environments. Oral presentation (not presenting author). Society for Integrative and Comparative Biology. Jan 2009.

Waldrop LD, Reidenbach MA, Koehl MAR. Oral presentation. Fluid dynamics of the blue crab antennule. Society for Integrative and Comparative Biology.  Jan 2008. Best Student Paper Award.

Waldrop LD, Kier WM. Flow visualization in the suspension feeding polychaete Spirobranchus giganteus. Poster. Society for Integrative and Comparative Biology. Poster presentation. Jan 2007.

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