Comments on: Why are stabby mantis shrimps so much slower than punchy ones?

By: Edward Tubb

Edward Tubb — Sat, 24 Nov 2012 18:45:17 +0000

This article got me thinking… energy gets stored when you snap your fingers, too. Which begs the question: how fast does a human middle finger get when snapped against the pad of the thumb?

Well, there’s video here of a finger snap at 2000 frames a second: http://courses.ncssm.edu/hsi/hsvideo/snap.wmv

It’s not perfect, but the period from the middle finger leaving the thumb to smacking the pad is something in the range of 12 and 20 frames (starts at about frame -10 and ends somewhere between frame 2 and frame 10).

That’s 12-20 frames over a distance of, say, 5 cm. That works out to 6 – 10 ms over 5 cm, which works out to between 5 and 8 m/sec.

As a ballpark guess, I’d say that’s not too shabby. The speed of the finger likely peaks a fair bit faster than that. Somebody grab a high speed camera and a ruler!

By: Thinkyhead

Thinkyhead — Thu, 22 Nov 2012 19:31:43 +0000

Nature is conservative, so if fast enough is fast enough then fast enough will do. A secondary consideration would be stealth for these shrimp, so it may be that the stealth of slow stabbing vs ‘loud’ punching reinforces its being slower as well. A lot of subtle pressures in evolution.

By: MosesZD

MosesZD — Thu, 22 Nov 2012 13:48:08 +0000

F=MV + leverage. Nature understands these and doesn’t tell itself stories about big, manly muscles.

By: J

Thu, 22 Nov 2012 09:46:01 +0000

Fascinating article, and a fascinating and beautiful group of animals. I have seen them myself many times while diving in Southeast Asia.
One thing i noticed: in the last para, there seems to be an “s” where there should be a “t”: “extreme punches so generate extreme accelerations”.

By: David H.

David H. — Thu, 22 Nov 2012 02:28:14 +0000

Maybe the stabby-shrimp’s prey wear Holtzman generators as personal shields? Fast-moving blades won’t penetrate, but a slower, more practiced attack will gain entry.