| Value |
>=7
GPa
|
| Organism |
Cnidaria |
| Reference |
Nüchter T, Benoit M, Engel U, Ozbek S, Holstein TW. Nanosecond-scale kinetics of nematocyst discharge. Curr Biol. 2006 May 9 16(9):R316-8. p. R317 middle columnPubMed ID16682335
|
| Method |
Researchers mimicked the receptor potential
triggering nematocyst discharge
[ref 6 in article] by applying a short-step
depolarization and analyzed
discharge in >1200 instances
with an electronic framing- streak
camera (for details see Figure S1 in
Supplemental Data). They resolved
the ultra-fast phase of discharge
by capturing an intermediate
stage between the resting capsule
and the fully ejected stylet at an
exposure time of 200 ns and a
framing rate of 1,430,000 fps. |
| Comments |
Assuming constant
acceleration, researchers calculate that the
stylets hit the cuticle with a final
velocity (Vmax = a×t) of 18.5–37.1 m/s (BNID 105579).
At an average volume (V) of
1,860 µm^3 and a specific density
(?) of 1.24×10^6 kg/m3 [ref 7 in article], the
stenotele’s mass (m=?×V) is 2.3
ng. Since 40% of this mass gets
ejected along with the stylets, the
accelerated mass is about 1 ng.
This corresponds to an accelerating force (F=m×a) of 13.2–53.1 µN and
a kinetic energy (E =1/2×m×Vmax^2)
of 0.17–0.7µJ. Due to the extremely
narrow tip of stylets (tip radius
15±8nm), the pressure (F/area) at
a stylet’s tip can be estimated to
be more than 7 GPa, which is in the
range of technical bullets. Note-the following calculating 53.1µN/[p×(15nm)^2]=75GPa, a maximum value one order of magnitude greater. |
| Entered by |
Uri M |
| ID |
105581 |