Dracula ants possess fastest known animal appendage: the snap-jaw | Hacker News Reader

Dracula ants possess fastest known animal appendage: the snap-jaw

eurekalert.org

54 pointsDoreenMichele20 comments

Well, how this compares to the http://theoatmeal.com/comics/mantis_shrimp ?

The authors mention the mantis shrimp in the first sentence. So, presumably, the ant is faster.

>CHAMPAIGN, Ill. -- Move over, trap-jaw ants and mantis shrimp: There's a faster appendage in town. According to a new study, the Dracula ant, Mystrium camillae, can snap its mandibles at speeds of up to 90 meters per second (more than 200 mph), making it the fastest animal movement on record.

Uh, sorry, I don't know how I could have missed that!

The mantis shrimp is still absolutely savage

First line of the article is "Move over, trap-jaw ants and mantis shrimp". From wikipedia[0], the mantis shrimp claws move at 51mph vs the ant mandibles of over 200mph.

[0] https://en.wikipedia.org/wiki/Mantis_shrimp

From the paper at https://royalsocietypublishing.org/doi/10.1098/rsos.181447 it is 90 m/s vs mantis shrimp's 30 m/s.

> The duration of the snap movement is one thousand times shorter than the snap of a human finger and five thousand times shorter than the blink of an eye

Compared to other ants:

> The power-amplified mandible strikes of other trap-jaw ants, such as the genera Odontomachus and Myrmoteras, take three to sixty times longer than the snaps of Mystrium

And further:

> Snap-jaw ant mandibles exceed the velocities and accelerations of other arthropod power-amplified movements, including trap-jaw spider chelicerae (8.5 m s−1, 103 × g) [34], mantis shrimp dactyls (30 m s−1, 104 × g) [35], and froghopper jumps (4.7 m s−1, 102 × g) [36], and have 10–75 times the power density of these movements.

Seems like 30 m/s through water would be a lot harder to do than 90 m/s through air, but perhaps at those speeds things don't make sense any longer :)

Easy to find out - put the shrimp in the air and see how fast it goes.

Trap-jaw ants do this funny catapult thing: When they close their jaws at those speeds against an inamovible object... see yourself: https://www.youtube.com/watch?v=52XZ_zjl1ck

edit: A better image example https://www.youtube.com/watch?v=0lw3-kCBx50&t=9%3A41

It’s like they discovered rocket jumping.

The story's video has examples as well: https://www.youtube.com/watch?v=v9dsINb64Q0

Not just 50 feet, 50 LINEAR FEET stop the presses

Well it's not going to be square feet, unless they splatter when they land.

Anyone have any idea what that would do to a human finger, a demonstration of which was sadly missing from the video?

Remember that this is a slap more than a bite, so it may not do as much damage as you'd think.

I have some idea. I think the force of impact would be between 1 Newton and 10 Newton. That's saying the mass involved is between 0.001 g (typical mass of an ant) and 0.0001 g (because I don't know how much of the ant's actual mass is involved). The paper cites 10^6 g as roughly the top acceleration, which yields roughly between 1 N and 10 N of force. That's roughly between the weight of an apple and a 1 kg object. So, not much.

tldr; Jaw snap at 200mph which at this scale is comparable to warp 10

I wonder how many times they can do that before the action breaks their mandible or kills them?

The usual body-size oriented headline scaling is a fallacy, because energy relates to mass (be it striking force or metabolism), not length, and mass scales with volume, and volume scales to the third power of length for three-dimensional-ish shapes (which are most animals).

So, say, the human arm is perhaps 100 times larger, so the headline-scaled striking speed would be 9000 m/s. But it is also approximately a million times heavier. The ant would hit with 0.02 J, the human arm with over 200 MJ, a punch so strong you could literally stop (and presumably completely destroy) an airliner in landing approach with one blow.

Your explanation reminded me of this: https://youtu.be/_Qq6dQwLh1s

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