Bugs are extraordinarily successful. They’ve seen the dinosaurs come and go (land-based bugs have been around for at least 400 million years). You also can’t go past bugs in the broad sense (insects, spiders and so on) for sheer diversity as they make up around 75% of all known animal species. Beetles are the real stars here as around a third of animal species are beetles, and we’ll talk a little more about them later.

One of the keys to the extraordinary success of bug is the exoskeleton. We humans have our supporting skeletal framework on the inside, but bugs wear theirs on the outside. This can provide protection and resistance to water loss, and is infinitely adaptable, allowing bugs to cover a huge range of ecological roles. From scavengers and parasites to herbivores and carnivores – bugs really do it all and span a bewildering array of body shapes in doing so.

Bombardier beetles are like living machine guns, sending out a near boiling chemical spray at a rate of hundreds of pulses a second out of a nozzle located on the rear end. It’s a sure-fire way to get your enemies to leave you alone.

Dr Phil Sirvid

Beetles are a wonderful example of this variety. They all have a broadly similar body plan with chewing mouthparts and a hardened pair of wing-cases, but you only have to look at the selection of beetles on display in Bug Lab to get a taste for how that basic form is shaped for a variety of different purposes. For example, we have the male harlequin beetle with bizarrely long front legs used in pushing contests to compete for mates and territory. There’s a diving beetles streamlined body with legs adapted for easy movement through water. There are stag beetles with huge heads and jaws for jousting and at the other end of the scale there’s a beetle with a narrow head to make it easier to get into the shells of snails it hunts. There’s more to see than that, including our Exoskeleton hero in giant form, the bombardier beetle.

Our bombardier beetle is represented in rather whimsical fashion as a slide (and yes, adults are welcome to try it too). You blast out the bottom end, which is appropriate as that is the bombardier beetle’s claim to fame.  Bombardier beetles are like living machine guns, sending out a near boiling chemical spray at a rate of hundreds of pulses a second out of a nozzle located on the rear end. It’s a sure-fire way to get your enemies to leave you alone. It’s all fuelled by chemical explosions inside the beetle’s body. Hydroquinones and hydrogen peroxide are broken down by enzymes in a chamber. This reaction makes water, oxygen and a substance called para-quinone which is incredibly irritating and unpleasant. The reaction is explosive, releasing a lot of heat, vaporising a portion of the mixture and generating pressure as well. This pressure is enough to eject the spray and causes a flexible part of the chamber wall to close off like valve, saving the beetle from being blown up by its own weapon system. In Bug Lab there’s film of the inner workings of a blasting bombardier beetle made as part of Eric Arndt’s doctoral research. Eric needed a half-billion dollar machine called a synchrotron (a high-speed x-ray) to get the footage!  It’s thought that all the chemicals and systems involved are derived from the exoskeleton and the chemicals needed to harden them, as well as common beetle defensive chemicals.

Humans have long been inspired by exoskeletons and they’re a science fiction staple. After all, who wouldn’t want tough armour like a beetle or to be able to lift many times their own weight like an ant? While some companies are making lifter exoskeletons to help augment human strength, others like Auckland-based Rex Bionics are developing exoskeletal systems to help people walk again. Pak Kitae also gives us a novel solution for getting water out of thin air inspired by the fog basking beetles of the Namib Desert. These clever beetles are able to condense water out of morning fogs and channel it to their mouthparts, giving them enough moisture to see them through the heat of the day. Pak Kitae’s model may be just the thing for getting something to drink where ground water is not to be trusted.

Dr Phil Sirvid looks after the entomology collection at Te Papa and has an inordinate fondness for spiders. He is one of the swarm of people that helped develop the Bug Lab exhibition.


Bug Lab


Currently showing at Auckland Zoo, Bug Lab is a blockbuster science exhibition developed by New Zealand’s world-famous museum, Te Papa, with the Academy Award© winning Weta Workshop. Tickets on sale now.

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