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| Almond‑Smelling Millipede |
Introduction
Deep in the damp forests of the Pacific Northwest lives a creature that seems harmless at first glance, a chunky, flat-backed millipede decorated with yellow spots. But don’t be fooled by its colours: when disturbed, this millipede, Harpaphe haydeniana, sprays a puff of cyanide so strong it smells like almonds. Though not deadly to humans, this little creature can harm birds and rodents.
Who Is the Almond‑Scented Millipede?
Millipedes belong to the class Diplopoda and are known for their long, segmented bodies and many legs. But Harpaphe haydeniana stands out, not just for its bold yellow patterns on a dark body, but for its powerful chemical defence. Reaching up to 4–5 cm in length, the yellow‑spotted millipede coils tightly when threatened.
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| Almond‑Smelling Millipede |
Almond Aroma: A Potent Warning
This millipede’s most unique weapon is hydrogen cyanide, a potent poison. When threatened, it secretes this compound, which smells distinctly like roasted almonds. The level of cyanide is too small to kill a human, though it may cause skin or eye irritation. However, it’s lethal to smaller forest animals such as birds and rodents. One Appalachian relative produces enough to kill a pigeon 18 times over.
How It Stays Alive
Despite its toxic spray, H. haydeniana remains unharmed by its own poison. The millipede neutralises the cyanide internally, converting it into harmless substances before it can affect itself.
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| Almond‑Smelling Millipede |
Lifeline of the Forest Floor
Far from being just a chemical weapon, cyanide is a survival tactic that allows these millipedes to thrive. With few predators left, they feed freely on leaf litter, mainly fallen fir and spruce needles, alongside decaying plant matter and fungi. Their activity shreds and recycles organic material, converting nutrients back into the soil and boosting forest health. In some forests, densities can reach up to 90 individuals per square metre. These millipedes are keystone organisms in nutrient cycling.
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| Almond‑Smelling Millipede |
Final Thoughts
The yellow‑spotted millipede is a surprising blend of delicate beauty and deadly defences. Its almond-scented cyanide spray not only deters predators but also ensures its continued role as a leading decomposer in forest systems. Next time you stroll through leaf‑covered trails, pause and consider the micro-hero at your feet, armed with cyanide, nourisher of forests, utterly immune to its own toxic gift.
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