Bombardier beetle defense mechanism

A Bombardier beetle produces and stores two reactant chemical compounds, hydroquinone
and hydrogen-peroxide in separate reservoirs in the rear tip of its abdomen. When
threatened, the beetle contracts muscles that force the two reactants through valved tubes
into a mixing chamber containing water and a mixture of catalytic enzymes. When combined,
the reactants undergo a violent exothermic chemical reaction raising the temperature to near
the boiling point of water. The corresponding pressure buildup forces the entrance valves
from the reactant storage chambers to close thus protecting the beetles internal organs.
The boiling, foul-smelling liquid partially becomes a gas (flash evaporation) and is expelled
through a outlet valve into the atmosphere with a loud popping sound. The flow of reactants
into the reaction chamber and subsequent ejection to the atmosphere occurs cyclically at at
a rate of about 500 times per second and with the total pulsation period lasting for only a
fraction of a second.These reactions release free oxygen and generate enough heat to bring the mixture to the
boiling point and vaporize about a fifth of it. Under pressure of the released gasses the valve
is forced closed, and the chemicals are expelled explosively through openings at the tip of
the abdomen. Each time it does this it shoots about 70 times very rapidly. The damage
caused can be fatal to attacking insects and small creatures and is painful to human skin.