Bombardier beetle self-defence

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Bombardier beetles have a unique means of self-defence, seeing off predators by blasting them with a disorientating caustic jet of steam and liquid. A violent explosion erupts from the rear end of the insect when two chemicals are combined and then catalysed.

The concentrated substances are secreted from glands into a reservoir where they are mixed inside the creature’s abdomen. When the beetle feels threatened a muscular valve then forces the concoction into a second chamber. Here a catalyst causes an exothermic reaction that raises the temperature of the liquid to boiling point.

A Bombardier beetle firing in self-defence

A Bombardier beetle firing in self-defence

It is then ejected under great pressure out the tip of the insect’s abdomen. This turret ejector can aim the stinky stream in all directions as it uses muscles to swivel the nozzle. The blast of fluid is released in super-fast pulses up to 500 times per second to prevent the beetle itself from being scalded.

The noxious jet of boiling fluid, which is also extremely smelly, confuses and, in some cases, can even immobilise the would-be assassin giving the beetle plenty of time to make its escape.