Maggot Skin Strengthens As It Dries

a blowfly maggot, with an iridescent body, red eyes and transparent wings, stands on a dry yellow leaf

Biological Strategy

Blow fly

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

Modify Material Characteristics

The materials found in living systems are variable, yet often made from the same basic building blocks. For example, all insect exoskeletons consist of a material called chitin. Because material resources are limited, each material within or used by a given living system must frequently serve multiple purposes. Therefore, living systems have strategies to modify materials’ softness, flexibility, and other characteristics. To ensure survival, the benefits of these modifications must outweigh the living system’s energy and material expenditure to generate them. For example, spiders store the liquid components of spider silk in a gland, converting them into silk thread when needed. Some threads have different characteristics, such as elasticity and UV reflectance, than others.

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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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Skin of blowfly maggots grows more waterproof as it dries because it forms strong, stable, cooperative structures when water is reduced.

Image: Dan Leiberman / Hidden Wonders /

“The cuticle of a maggot goes through a mechanical transition when it dries, increasing in stiffness by about an order of magnitude (e.g. from 0.5 GPa to 5 GPa) as the water content drops from about 1 g/g (weight of water per unit dry weight) to 0.4 g/g. Thus stiffness represents the loss of freezable water and is more or less diagnostic of a material stabilized by hydrogen bonds. Further loss in water results in a smaller increase in stiffness. In natural systems the water content is controlled by the addition of phenolic residues, resulting in tanning or sclerotisation, which drives the matrix components towards co-operative interaction and makes the material permanently waterproof.” (Vincent 2004:4)

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