פרופ' רועי הולצמן

Functional morphology and the evolution of complex functional systems. Biomechanics and hydrodynamics of suction feeding in fishes. Hydrodynamics determinants of predator-prey interactions. Effects of ecology and functional architecture on rates of evolutionary morphology.

המחקר שלי מתמקד בביו-מכניקה עם תשומת לב ספציפית להידרודינמיקה של האכלת יניקה בדגים, ולגורמי ההידרודינמיקה של אינטראקציות טורף-טרף. אני גם מתעניין באופן נרחב במורפולוגיה פונקציונלית ובאבולוציה של מערכות פונקציונליות מורכבות, במיוחד ההשפעות של אקולוגיה וארכיטקטורה פונקציונלית.

Hydrodynamic constraints on suction feeding in low Reynolds numbers:

Newly hatched fish subsist on a limited supply of yolk and thus must encounter and successfully capture food before depleting their energy resources. To capture their prey, larval fishes close the distance to their prey by rapidly swimming towards it while rapidly opening their mouth to generate a flow of water external to the mouth. This feeding mode, termed “suction feeding”, is thought to be the universal feeding mode in larval fishes. The suction flow is the key to suction feeding success, because it draws the prey item into the predator’s mouth, countering any escape response of the prey. Because of the difficulties inherent in making direct measurements and observations on small animals such as larval fishes, very little is known about these flows, how those flows are translated to prey capture, and whether those change during early development. Our goal is to identify the physical constraints of feeding efficiency in larval fishes, and how those constraints effect larval survival. Using particle tracking velocimetry and computational fluid dynamics, experiments with live fishes, and a range of modeling approaches we strive understand how the hydrodynamic constraints imposed on larvae shape their performance and ultimately their survival. read the paper HERE of e-mail me for a copy 

Navigation in Mexican blind cave fish

With Shimrit Perkol-Finkel and Gregory Zilman, we report a new mechanism of non-visual navigation in the Mexican blind cavefish. We show that this species uses mouth suction to purposefully emits detection signals, and modulates their frequency and emission rate in different states, a hallmark of pulse-based navigation mechanisms such as echolocation. These detection signals, generated by sucking water into the mouth, are several orders of magnitude stronger than previously estimated for the corresponding stimuli induced by the fish’s gliding body. This novel mechanism can thus explain inconsistencies between observed behaviors of the Mexican blind cave fish and current theory of “hydrodynamic imaging”. Read the paper apears in JEB or e-mail me for a copy.

The relationship between morphological disparity and function in the feeding mechanism of fishes

The nature of the relationship between structure and function is a fundamental question in evolution. In this research, we use two hi-speed video cameras to get 3D video of fish eating in the reef, in order to quantify morphological variance of certain traits in the multi-variant complex mechanism of suction feeding. In addition, we use a first principles based mechanistic model to assess each traits’ contribution to feeding success (function). We expect the comparison between morphological and functional variance to shed some light on the intricate relationship between structure and function.

China, V and Holzman R. (2014) Hydrodynamic starvation in first-feeding larval fishes. PNAS 111, 8083–8088. PDF

Holzman, R., D.C. Collar, R.S. Mehta. and P.C. Wainwright. (2011). Functional complexity mitigates evolutionary trade-offs. American Naturalist 177 :E69-83. PDF

 

Higher Education

1995-1998: Hebrew University of Jerusalem, Biology Bachelor’s degree, Graduated with distinction (MAGNA CUM LAUDE).

1999-2001: Hebrew University of Jerusalem, Dep of Evolution, Systematics and Ecology, Master’s degree. Supervisor: Prof. Amatzia Genin. A “direct route” transfer to Doctorate program (no thesis)

2001-2006: Hebrew University of Jerusalem, Dep of Evolution, Systematics and Ecology, Doctorate degree. Supervisor: Prof. Amatzia Genin. 

 

Academic positions 

2016- Present: Associate professor, the school of Zoology in Tel Aviv University and the Inter-University institute for marine science in Eilat.

2010-2016: Senior lecturer, the department of Zoology in Tel Aviv University and the Inter-University institute for marine science in Eilat.

2007-2010: Post-doctoral fellow. University of California in Davis, Dept. of Evolution and Ecology. Host: Prof. Peter Wainwright.

2006-2007: Rothschild post-doctoral fellow. University of California in Davis, Dept. of Evolution and Ecology. Host: Prof. Peter Wainwright.

 

Current Members

Dror Malul, Ph.D. Student
2020-today:   The Mechanical Properties of Coral Tentacles and their Contribution to the Efficiency of Mass Transfer . Co-advised by Prof. Uri Shavit

Tal Perevolotsky, Ph.D. Student
2020-today:   biomechanics of algal grazing in Coral Reef fish . Co-advised by Prof Amatzia Genin

Michaela Kolker, Ph.D. Student
2016-today:   Morphological evolution in larval fishes

Tamara Gurevich, Technician
2012-today:   Lab manager; in charge of molecular laboratory

Christopher Martin, Other
2019-today:   Research Cooperator- Scientist

Past Members

Victor China, Ph.D. Student
2011-2017:   Thesis: Hydrodynamic constraints from egg to the post settlement stage of marine fishes

NOA MOSHKOWITZ, M.Sc. Student
2011-2013:   Adaptation for prey capture in fish- the importance of gape size and jaw protrusion

Tal Keren, M.Sc. Student
2012-2015:   The relationship between morphological disparity and function in the feeding mechanism of fishes

Liraz Levy, M.Sc. Student
2014-2016:   Characterizing spatial and temporal flow patterns in suction feeding fish larvae

Miri Zilka, M.Sc. Student
2012-2015:   Hydrodynamics of suction flows in larval fishes

Stan Yavno, Postdoc
2015-2017:   Body size selection in larval fishes; Mechanical transgressive segragation

Liat Koch, Postdoc
2015-2018:   characterising larval starvation using hypothalamic appetite-stimulating neuropeptides

Corrine Jacobs, Ph.D. Student
2015-2020:   Diversity of suction feeding flows

Lior Avidan, M.Sc. Student
2014-2016:   Effect of flow speed on feeding success of reef fish

Noam Sommerfeld, M.Sc. Student
2016-2019:   Predator prey interactions between larval fish and evasive prey