Combustion Chamber Sprays Scalding Liquid

a reddish brown and black beetle walks on a tan rocky surface

Biological Strategy

Contracted bombing beetle

AskNature Team

Image: Katja Schulz / Flickr / CC BY - Creative Commons Attribution alone

Expel Liquids

There are various reasons living systems discharge liquids, such as to defend themselves, to avoid liquid buildup that can cause decay, to eliminate waste, or to dry off. Because liquids cannot be effectively moved through pushing, a different kind of force is needed to expel them. Creating that force requires energy, so living systems must have efficient strategies worth the energy investment or use an outside force (such as gravity). This typically entails strategies that build up pressure or use other forces to propel liquids away. An example of a living system that expels liquids is the scallop. This creature moves through water by clapping its shells together, generating a water jet that propels it in the opposite direction.

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Transform Thermal Energy

Heat is necessary for survival, but too much of it can be damaging to an organism. Explore the ways different living things have adapted to use or transform different types of thermal energy.

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Insects

Class Insecta (“an insect”): Flies, ants, beetles, cockroaches, fleas, dragonflies

Insects are the most abundant arthropods—they make up 90% of the animals in the phylum. They’re found everywhere on earth except the deep ocean, and scientists estimate there are millions of insects not yet described. Most live on land, but many live in freshwater or saltwater marshes for part of their life cycles. Insects have three distinct body sections: a head, which has specialized mouthparts, a thorax, which has jointed legs, and an abdomen. They have well-developed nervous and sensory systems, and are the only invertebrate that can fly, thanks to their lightweight exoskeletons and small size.

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The combustion chamber of the bombardier beetle ejects scalding liquid by having a heart-shaped, long, narrow ejection tube.

“The aim of the study is to show the advantages of the naturally occurring design and identify the main parameters important for the high efficiency discharge. The results indicate that this rather unusual design of beetle combustion chamber does indeed have better performance in term of efficiency of mass ejection. This is primarily due to the heart shaped combustor combined with a long narrow ejection tube…The results support the idea of a possible practical use for pilot ignition systems, such as re-igniters in aircraft gas turbines and automotive safety air bag ignition devices.” (Collins 2004:227)