explain the very rough surface of Gators and Crocs, hydrodynamically

Seems all those bumps would create a lot of drag, and some species such as Salty Crocs spend lots of time swimming long distance in open ocean, yet still have LOTS of bumps which don't seem to serve much purpose.
Do the ridges and bumps serve some body temp regulating function, similar to the "sail back" on some early dinosaurs? Those look like if they could swim they might use their sails as sails, but I guess that never happened.

 

Um, why would the lumps and bumps have anything to do with Hydrodynamic efficiency ? Looking at the teeth of other crocs, a thick skin isn't all about swimming ability, I would have thought.
Also, dark and raised skin probably absorbs heat faster, for a cold blooded animal.

 

And I don't think it has anything to do with the dimples on spherical golf balls since crocs are streamlined.

 

I thought it was going to be a thread about water shoes!

 

It's an ideal system for lazing at the water surface, looking like a log with chunky old bark on it, being warmed in the sun, watching everything that moves, waiting for someone to let their dog off the lead to go for a swim. Nuggets ! They are immensely strong and very quick in bursts, and use their tail to swim like a fish long distances. Their underside is like smooth tiles, so minimal drag when on the surface. And also the lumpy back skin may look too tough and dangerous to predators, deterring them from trying before they even see the teeth. Never smile at a crocodile.

 

Hydrodynamically, bumps are usefull for flow control, creating turbulence in the boundary layer, making it more stable than a laminar one. I don't know, though, if it's the main purpose of bumps on Gator and Crocs.
A little out of subject, but very kind to crocs, are the people in this village Sacred snappers: The African village where crocodiles are revered residents http://www.chinadaily.com.cn/a/201806/20/WS5b29beb6a3103349141dd433.html#:~:text=BAZOUL%2C%20Burkina%20Faso%20%2D%20Crocodiles%20may,one%20of%20the%20fearsome%20reptiles., showing the better of a strong and intelligent relationship among two of the most deadly creatures of the Planet Earth : The Crocodile and the Man.

 

The bumps could create channels of water when they surface and submerge slowly, dissipating the ripples which would normally be seen when something breaks the surface. It's a hydrodynamic stealth adaptation maybe. They've been the same for millions of years, so they must be of some benefit. Do the Clingons have lumpy backs to go with their faces ?

 

Various sources, non of them *hugely* authoritative, tbh suggest a number of functions to the nubbins , aka 'scutes': The TLDR takeaway is essentially: Physical protection, temperature regulation, moisture control, sensory information (lots of nerve endings - water vibration and pressure, temperature) and, yes, aiding movement. The suggestion is they act like paddles with the movement of tail. Not sure how convincing I find that, but hey.

Crocodilia - Wikipedia https://en.wikipedia.org/wiki/Crocodilia

Osteoderm - Wikipedia https://en.wikipedia.org/wiki/Osteoderm

The Many Purposes Of A Crocodile’s Scutes | Reptilecity https://reptilecity.com/the-many-purposes-of-a-crocodiles-scutes/

Alligators and Crocodiles Have Scales? (Croc Scutes Explained) – Fauna Facts https://faunafacts.com/crocodiles/do-alligators-crocodiles-have-scales/

 

Evolution always has infallible reasoning. Our lack of ability to understand that reasoning is the stumbling block.

 

Duckbill platypus is one I don't understand, ha!

Some species do go extinct, although it might not be due to poor hydrodynamic modeling...

 

My younger lad has just finished his degree in biology. When I struggle to grasp the things he talks about he says things like 'Dad evolution doesn't have intent - its just chance and maths'

 

And unlimited iteration. Things that don't work don't make it.

 

Sure they do. They come along with the good stuff. Starting with "junk dna",
You can Google plenty of human and animal vestigial traits.

 

Have to be more careful what words you use on this forum than on youtube comments. What I meant to convey is life forms that don't work don't make it. If the vestigial trait gets in the way of survival it will not remain.

 

Do you know the difference between Google and Youtube ?
Not that there aren't many great lectures available on YouTube to0.

"If the vestigial trait gets in the way of survival"
is NOT the same as
" Things that don't work don't make it."