one of the fastest animals on earth

[Ironsheikh]

I just saw it on animal planet one of the fastest animals-- .5 micro sec fast-- as fast as a small caliber bullet---

 

[moggyhill]

neat

 

[mightymouse]

to be more exact a large species around 6 inches from what i have read can approach the speed of a 22 caliber bullet which travels at about 1400 fps(feet per second)

 

[rwhhunt]

The show on "Most Extreme-Speed" on Animal Planet was very cool. They had a peacock battle a fiddler crab, and shatter glass on camera. BUT they didnt even talk about the other fascinating aspect of MS, like their visual systems, intelligence, phosphorensce, etc. They could make a whole hour show on these guys!

 

[Absint Reefer]

I would watch it

 

[jeffbrig]

I just saw another Animal Planet show with a mantis tonight. It was a show callled "Spy on the Wild", basically a show about observing animals with micro cameras and the like. In a segment on fast animals, they included the mantis.

A high speed camera captured the 'bashing' attack of a mantis, and it was played it back in slow motion. Just before impact, you could clearly see a bubble appear in front of the hammer appendage. They stated this was caused by some form of 'cavitation', but that doesn't quite make sense to me. Very cool to watch, though...

They also used some sort of device to measure the force of the strike, and said it was on the order of 200 lbs. Ouch!

 

[rwhhunt]

Thats interesting about the cavitation. It seems that this process is also performed with Pistol shrimps. When they fire their claw it creates a cavitation and pressure wave that knocks out opponents with a underwater "sonic boom". I also saw a show on the science channel about cavitation with underwater bullets and HIGH SPEED torpedos/vessels. The cavitation allowed the ship or bullet to be surounded by a cavity of air which reduced drag coefficeints drasticly! Maybe the mantis's club utilizes this reduction in drag to achieve even faster speeds (especiialy considering the density of water vs air), as well as a sonic mechanism that can stun and shatter hard shells of prey... The combined aspects of both extreme speed by reduced drag, and a strong pressure wave may shine light on how that little club can acheive impact force comparable to a small calibre firearm....
Sounds like a nice an interesting research topic... Roy any thoughts?!?!??????

 

[moggyhill]

you are the physics student, sounds like a good project to me.

 

[rwhhunt]

Excellent, All I need now is MORE MANTISS! Lots more! I would love to check out Roy's lab at Berkeley! His work is really fascinating! I wouldnt be suprised if the military would be interested in some bioengineered pracitical application of mantis clubs..but then again they have bullets, rockets, lasers, directed energy weapons, etc... I guess mechanical weapons are things of the past...

 

[moggyhill]

I don't think so, they still use dolphins.

 

[rwhhunt]

Thats True! Its amazing what this guys can do! Very Intelligent

 

[jeffbrig]

rwhhunt, admittedly it's been quite a few years since I took any physics class, maybe you can help me to understand this. I'm used to cavitation occurring in a low pressure zone (i.e. back side of an impeller/propeller), the low pressure causing a transformation from liquid to gas. However, I would expect the leading edge of a mantis strike to be under high pressure. Does this somehow change just before impact due to the movement of the water, or is there some other mechanism I'm not envisioning?

BTW, they did say this cavitation bubble caused a double impact, increasing the power of the blow, so you were right on that as well.

 

[Gonodactylus]

Sheila Patek and I have been working on this for the past year. The video that you saw was shot in my lab and the cavitation actually occurs just after the impact of the dactyl heal striking the surface of the load cell. The cavitation is indeed formed by low pressure. As water is forced away from between the dactyl and the plate, it greatly accelerates. If you remember Bernulli's Principle (sorry, I never could spell), the faster the flow, the lower the pressure. This caused the vapor bubbles to form, then collapse. When they collapse, tremendous amounts of energy are released including sound, heat and even light. The destructive power of the cavitation is almost as great as the physical impact of the dactyl and certainly increases the destructive power of the strike. We will be submitting a paper on this in the next few days. For now, this is about all I can say.

Roy

 

[rwhhunt]

WOW! How cool! If your allowed to say, have you been able to photograph any of the photo-emissions (im assuming a little IR?...) from the strike? Where will your new paper be available? An interesting experiment would be to determine the velocity at which the mantis's club begins to invoke cavitation, then measure the difference (probably by means of constructing a simple yet similiar-in shape, mass, density, etc artificial club) in impact force between say 5 meter/s below the cavitation threshold, and 5 m/s above it. Take a couple other plots above and below these points to graph a linear plot, if the graph seems to show a drastic increase or some non-linear effect in impact force around the cavitation velocity, one could conclude that it is a component of the strike force and could extrapolate approximately how much of an increase of force is the cavitation responsible for...

 

[jeffbrig]

Thanks for the info Roy, that makes perfect sense. I certainly did not catch the detail that the cavitation was occuring just after the impact (it is admittedly hard to tell, even with high speed video).

Gotta love RC, though. I post about a show I watched on TV the other day, and get a reply from the person doing the actual research!

 

[Gonodactylus]

We will progably go for a high profile journal such a Science, but if that fails J. Exp. Biology? The photon emission of snapping shrimp cavitation has been measured (broad spectrum visible), but we have not tried with the stomatopods since it is difficult to get them to strike in the dark. I felt good being able to hand hold a camera recording the strike impacting a plate at 100,000 fps.

Roy

 

[rwhhunt]

100,000 feet per second?!? Wow I think that is faster than other estimates ive heard! Keep us posted on when and where you article is being published! Thanks!

 

[got chow]

I think Roy meant the camera was rolling at 100,000 Frames Per Second? Regular cameras roll at a much slower 30 FPS, and to capture something in slow motion, you need a MUCH faster camera. 100k FPS is smokin' fast, and you can slow down the film a lot by using such a high FPS camera.

That's assuming what Roy meant was frames per second... I'm not sure.

 

[rwhhunt]

that has to be it, it makes Much more sense... I think 100,000 feet per sec is still something like ~30,000 meters/sec which is like 19 miles/sec!!! VERY unrealisitic... thats about C (the speed of light)divided by ~160...