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George Lauder @georgelauder.bsky.social · 04/02/2025

Not yet, but the keels of carangids are very interesting too!

George Lauder @georgelauder.bsky.social · 03/02/2025

5. We hypothesize that tuna keels with their dorsal and ventral tubules act as flow sensors, perhaps providing information on tail beat frequency, amplitude, force, and water flow dynamics over the caudal region of the tuna body during locomotion.

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George Lauder @georgelauder.bsky.social · 03/02/2025

4. The keel lateral line canal (pink color) is quite strange: neuromasts are surrounded by modified scales (shown in blue), and keels have an odd set of elongated skeletal elements posteriorly. Tuna keels are clearly mechanosensory.

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George Lauder @georgelauder.bsky.social · 03/02/2025

3. Now, a team led by @juliachaumel.bsky.social and published in iScience @cp-iscience.bsky.social shows that tuna keels have a sensory function too! Each keel has a peculiar lateral line canal with small tubules that extend to the upper and lower keel surfaces (www.cell.com/iscience/ful...

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George Lauder @georgelauder.bsky.social · 03/02/2025

2. And here’s a view of the caudal fin and keels from behind during #tuna locomotion. Our previous work has shown that the keels decrease power requirements during swimming, likely by reducing lateral forces and yaw torques. But wait, there's more!

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George Lauder @georgelauder.bsky.social · 03/02/2025

1. #Tuna have well-developed bilateral keels extending to the right and left sides at the caudal peduncle area just in front of the tail. This movie shows the keel area during locomotion in yellowfin tuna. What is the function of keels in #tuna? A🧵 and new hypothesis.

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Reposted by George Lauder

Júlia Chaumel @juliachaumel.bsky.social · 28/01/2025

Our new paper is out as OA! shorturl.at/BueUy Tuna keels aren't just for hydrodynamics—they're mechanosensory! 🐟 They contain a modified lateral line, possibly adapted to detect stimuli in high-noise environments @georgelauder.bsky.social @jackiew8.bsky.social + Dylan Wainwright + Connor White

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George Lauder @georgelauder.bsky.social · 22/01/2025

Thanks, yes. The tail is an amazing sensory structure, but nobody has looked before!

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George Lauder @georgelauder.bsky.social · 22/01/2025

We propose that the ray tail acts like a “hydrodynamic antenna” providing detailed information to the ray on water movement behind the body. This video shows the effect of moving water near the tail of a cownose ray as it passes by.

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George Lauder @georgelauder.bsky.social · 22/01/2025

There are paired lateral line canals along both sides of the entire length of the tail with a remarkable branched structure that ends at the tail surface with clusters of pores. Each canal has a continuous neuromast that extends the entire tail length!

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George Lauder @georgelauder.bsky.social · 22/01/2025

What is the function of the elongate tail in elasmobranch #rays? A 🧵 and a new hypothesis. A paper with @juliachaumel.bsky.social in @royalsociety.org Proceedings B (shorturl.at/PmfYD) shows that the tail of cownose rays (and a few other species studied so far) has an elaborate lateral line.

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George Lauder @georgelauder.bsky.social · 31/12/2024

What is the significance of the tremendous diversity of #shark skin #denticles? Presenting our experimental approach to understanding this at the Atlanta #SICB2025 meetings. Come to the session for all things shark skin!

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George Lauder @georgelauder.bsky.social · 15/12/2024

Thanks Valentina! The manuscript should be out soon ... we're waiting for proofs now.

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George Lauder @georgelauder.bsky.social · 28/06/2024

Overall this supports the new “turbulence sheltering hypothesis” for why fish might group together, especially during active migratory movements where water flow is chaotic and turbulent: fish in a school can save a considerable amount of energy compared to swimming alone.

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George Lauder @georgelauder.bsky.social · 28/06/2024

This occurs largely because individuals within the school alter the flow environment with their undulating bodies and proximity: fish within schools in turbulence swim more closely together as speed increases compared to schools in laminar flow:

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George Lauder @georgelauder.bsky.social · 28/06/2024

We showed that swimming in turbulence by fish schools dramatically reduces both the cost of swimming (orange curve, left panel, compared to purple curve), and the cost of transport (right panel) when in turbulence compared to individuals swimming alone.

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George Lauder @georgelauder.bsky.social · 28/06/2024

@TheYangfanZHANG led the project with @mcalicc7, @HungtangK, and Prof. Rui Ni @JohnsHopkins to test this hypothesis, comparing individuals swimming alone to energy use by small schools swimming in turbulent conditions: paper at tinyurl.com/yc764d74

tinyurl.com

Collective movement of schooling fish reduces the costs o...

What are the benefits of collective behavior? This study ...

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George Lauder @georgelauder.bsky.social · 28/06/2024

Most studies of fish schooling have involved swimming in still or slowly flowing water. But fish in groups often move through turbulent water conditions. Could swimming collectively act to mitigate the increased energy needed to swim in turbulence?

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George Lauder @georgelauder.bsky.social · 28/06/2024

A new idea: the “turbulence sheltering hypothesis”. Fish in a school could modulate surrounding turbulence so that chaotic fluid motion increasing swimming cost is less. Fish in a group would use less energy compared to swimming alone in turbulent conditions.

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George Lauder @georgelauder.bsky.social · 28/06/2024

Why do #fish swim in #schools? A🧵and new hypothesis. Schooling could help fish avoid predators, navigate, communicate, find mates and food, and save energy. Here we propose and test a new hypothesis: tinyurl.com/yc764d74

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George Lauder @georgelauder.bsky.social · 21/02/2024

There are a wide variety of hydrodynamic mechanisms that allow energy savings as fish swim near each other and in each others wake, and fish in schools are changing relative positions dynamically through time.

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George Lauder @georgelauder.bsky.social · 21/02/2024

Our results also cast doubt on using only simple kinematic metrics such as tail beat frequency as a proxy for energy savings: fish in schools can save energy even when tail beat frequency does not change.

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George Lauder @georgelauder.bsky.social · 21/02/2024

We also showed that schooling fishes saved relatively more energy as they moved faster compared to solitary fish, and that the cost of transport curve is also U-shaped with clear benefits to swimming in a group.

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George Lauder @georgelauder.bsky.social · 21/02/2024

By swimming both schools and solitary fish over a wide range of speeds, we showed that (1) very low speed swimming involves as much energy use as swimming at 3 body lengths/sec, and that the metabolism-speed curve is U-shaped over this speed range.

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George Lauder @georgelauder.bsky.social · 21/02/2024

And, we need to study school and solitary swimming over a range of speeds and measure energy use both during swimming and during post-exercise recovery to quantify EPOC: the energy used to sustain swimming at high speeds beyond the aerobic threshold.

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George Lauder @georgelauder.bsky.social · 21/02/2024

Do #fish swimming in a #school actually save energy? A🧵on this as our paper in @eLife elifesciences.org/articles/90352 by @TheYangfanZHANG addresses this question. This is a challenging issue to study: energy use by a school should be compared to solitary locomotion

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George Lauder @georgelauder.bsky.social · 21/02/2024

Do #fish swimming in a #school actually save energy? Our paper on this in eLife elifesciences.org/articles/90352 addresses this question. This is a challenging issue: energy use by a school needs to be compared to solitary locomotion on a per gram basis under the same swimming conditions.

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George Lauder @georgelauder.bsky.social · 02/01/2024

The shark #denticle #multiverse will be on display at #sicb2024 this week. See talks in the @SICB_DCB_DVM sessions. So much diversity, so little time ... below the #ontogeny of sleeper shark denticles from Vaz et al. 2023: mdpi.com/1424-2818/15...

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George Lauder @georgelauder.bsky.social · 02/01/2024

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George Lauder @georgelauder.bsky.social · 02/01/2024

Getting ready for #SICB2024, and all things #shark skin! Testing patches of skin to measure the shear stress (friction) of water moving over the skin, and how #denticle orientation alters flow patterns.

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George Lauder @georgelauder.bsky.social · 02/01/2024

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George Lauder @georgelauder.bsky.social · 22/12/2023

Yes indeed, those are dermal denticles! We're doing a lot of research on their structure and function.

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George Lauder @georgelauder.bsky.social · 21/12/2023

Thank you, yes! Please do add me. Shark postings coming soon!

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George Lauder @georgelauder.bsky.social · 19/12/2023

Our accessible Sharks Summer REU is running in 2024. Unique opportunity for disabled undergraduates interested in sharks, paleobiology, developmental biology, and bio-inspired design. Apps due Jan 19. #NSFFunded #DisabledInSTEM. Please repost and spread the word! accessiblesharks.wordpress.com

accessiblesharks.wordpress.com

Accessible Sharks REU

Accessible Sharks: A Summer Research Experience for Disabled Undergraduates Image is a grayscale scientific illustration of a smooth dogfish (Mustelus canis). on a white background. The image was orig...

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George Lauder @georgelauder.bsky.social · 19/08/2023

This past summer Elizabeth Sibert, Gareth Fraser, and I ran an "Accessible Sharks" REU program as part of our NSF grant. Story here ... and we're running it next summer too! news.harvard.edu/gazette/story/2023…

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George Lauder @georgelauder.bsky.social · 24/03/2023

One limitation of our study: the thrust wake was mostly two-dimensional since it was generated by an upstream flapping foil. It is still to be determined if fish can take advantage of a thrust wake when that wake is more 3D and on the order of fish body height. More to come!

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George Lauder @georgelauder.bsky.social · 24/03/2023

We showed that fish tune their tail beat to the foil, intercept vortices, slightly alter body motion, and tune phase based on their distance from the foil. Due to how the head intercepts the foil wake we propose that fish can reduce swimming costs even in a thrust wake.

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George Lauder @georgelauder.bsky.social · 24/03/2023

@rthandiackal and I conducted experiments to simplify the in-line swimming condition and allow a fish to swim in a thrust wake generated by a flapping foil (the @eLife link makes it easy to see the videos embedded into the main text): elifesciences.org/articles/81392

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George Lauder @georgelauder.bsky.social · 24/03/2023

The difference between fish swimming in reduced flow (a drag wake) and in-line (with a thrust wake impacting the following fish) is nicely summarized by the graphic below from the commentary by @icouzin and Liang Li in @eLife: elifesciences.org/articles/86807

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George Lauder @georgelauder.bsky.social · 24/03/2023

This would seem clearly to be disadvantageous, so in-line (tandem) swimming in fish has been thought to be bad, because leading fish generate a thrust wake that fish behind would encounter. This increased velocity should increase the energy required to swim.

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George Lauder @georgelauder.bsky.social · 24/03/2023

Why might #fish in a #school swim behind one another? A🧵.This question arises because being behind another fish involves #swimming in faster flow. A cyclist can draft because oncoming velocity is reduced. A thrust wake is like a cyclist facing a leader with a large fan.

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George Lauder @georgelauder.bsky.social · 02/01/2023

The #shark #denticle #multiverse is vast, and @MarBioMoll will present at #SICB2023 on ontogenetic changes in skin denticles in leopard sharks. So much variation and so few previous studies of denticle ontogeny @SICB_ @SICB_DCB_DVM

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George Lauder @georgelauder.bsky.social · 02/01/2023

Gearing up for the #SICB2023 meetings … first up is the #shark #denticle #multiverse! Talks by @dfbvaz and Tess Avery will describe remarkable changes in denticles during ontogeny in the Portuguese dogfish, accompanied by lots of variation around the body @SICB_ @SICB_DCB_DVM

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George Lauder @georgelauder.bsky.social · 17/06/2022

There are many methods that comparative biologists can use to understand the diversity of life: let’s make robotics one of them!

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George Lauder @georgelauder.bsky.social · 17/06/2022

The performance landscape for any behavior can be complex with more than one peak. Here’s one for swimming … it has two peaks! How would we determine this studying living species alone, without the ability to alter all experimental parameters to generate the surface?

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George Lauder @georgelauder.bsky.social · 17/06/2022

Three reasons why robotics should be part of our comparative toolbox: (1) Precise control so that only the trait of interest can be varied; (2) Direct measurement of energetic costs; (3) Quantification of the performance landscape.

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George Lauder @georgelauder.bsky.social · 17/06/2022

Designing a robotic mechanism where we can vary individual traits on demand avoids the challenge of uncontrolled variables. A robotic fish allows us to identify the effect of specific changes that would be impossible to study in a living fish: bit.ly/3mXyJz7

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George Lauder @georgelauder.bsky.social · 17/06/2022

The inability to isolate traits for comparison exemplifies the “ceteris paribus” challenge outlined by Dick Lewontin in the 1970s: ideally we should control all variables that are extraneous to the specific hypothesis at hand, and only alter the trait of interest.

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George Lauder @georgelauder.bsky.social · 17/06/2022

When making comparisons among organisms it is extremely challenging to isolate only the trait of interest. We could compare the function of a tuna and sunfish tail, but these two fish species differ in countless other traits.

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