biology

Harpaphe haydeniana

Harpaphe haydeniana is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Harpaphe haydeniana rather than just read about it. In short: Harpaphe haydeniana, commonly known as the yellow-spotted millipede, almond-scented millipede or cyanide millipede, is a species of polydesmidan ("flat-backed") millipede found in the moist forests along the Pacific coast of North America, from Southeast Alaska to California. The dark coloration with contrasting yellow-tipped keels warn of its ability to exude toxic hydrogen cyanide as a defense.

Key takeaways

Harpaphe haydeniana belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Harpaphe haydeniana to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Harpaphe haydeniana from memory before moving on to harder problems.

Reference excerpt

Harpaphe haydeniana, commonly known as the yellow-spotted millipede, almond-scented millipede or cyanide millipede, is a species of polydesmidan ("flat-backed") millipede found in the moist forests along the Pacific coast of North America, from Southeast Alaska to California. The dark coloration with contrasting yellow-tipped keels warn of its ability to exude toxic hydrogen cyanide as a defense. The cyanide secretions are not dangerous to humans, but can cause irritation and pain if it contacts sensitive areas such as the mouth, eyes, or nose. Despite the various common names given the species, the coloration pattern, cyanide defense, and associated almond scent occur in other flat-backed millipedes around the world.

Description Harpaphe haydeniana reach a length of 4–5 centimeters (1.6–2 in) when mature. The upper surface of the body is black to olive green, and is distinctively marked along the sides with patches of a yellowish colour. H. haydeniana has approximately twenty body segments, bearing a total of 30 (males) or 31 (females) pairs of legs. The difference between males and females is due to one pair of legs on the seventh segment in males being modified to form gonopods used for sperm transfer. Individuals may live for 2–3 years.

Distribution Harpaphe haydeniana occurs from southeast Alaska south to Monterey County, California, as far east as the Sierra Nevada mountains.

Ecology Harpaphe haydeniana is an important part of the forest ecosystem, breaking down leaf litter and freeing its nutrients for other organisms. It is commonly associated with redwood forests where many individuals may be found within a small area. Immature millipedes feed on humus. Harpaphe haydeniana has few predators, due to its aposematic coloration and its ability to secrete hydrogen cyanide when threatened. This behaviour gives rise to the common names "cyanide millipede" and "almond-scented millipede" (since cyanide smells of almonds), although cyanide secretion is not unique to H. haydeniana. Nonetheless, at least one species, the ground beetle Promecognathus laevissimus, is a specialised predator of H. haydeniana.

Similar species

Two other species of Harpaphe (H. pottera and H. telodonta) occur within the range of H. haydeniana, both with yellow-tipped paranota. H. telodonta (Humboldt and Del Norte counties, California) is slightly more brown in colour and has more strongly pointed keels while H. pottera (Mendocino and Humboldt counties) can only be distinguished by close examination of the male reproductive organs (gonopods). The genus Harpaphe is in the family Xystodesmidae, which contains several other species with similar markings, including North American species of Boraria, Chonaphe, Paimokia, Hybaphe and Montaphe. Exact species determination requires examination of the male gonopods, but the sharply pointed posterior corners of the paranota can help distinguish Harpaphe from Hybaphe and Chonaphe. Outside of North America, superficially similar species include Anoplodesmus saussurii which has been mistakenly called H. haydeniana, and Asiomorpha coarctata, the latter species being native to Southeast Asia but widely introduced around the world, including the American Gulf Coast region. The ability to secrete hydrogen cyanide is shared by other members of the Polydesmida, the largest order of millipedes.

References

External links Media related to Harpaphe haydeniana at Wikimedia Commons

Illustrations

Worked examples

Example 1 — a first encounter with Harpaphe haydeniana

Start with the simplest possible case. Write down what Harpaphe haydeniana claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Harpaphe haydeniana before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Harpaphe haydeniana ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Harpaphe haydeniana

In research: Harpaphe haydeniana appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Harpaphe haydeniana in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Harpaphe haydeniana is common in secondary-school and first-year university syllabi. It links to neighbouring topics Animals described in 1864, Aposematic species, Fauna of the Northwestern United States, so understanding it makes those chapters shorter.
In everyday life: Look for Harpaphe haydeniana outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Harpaphe haydeniana in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Harpaphe haydeniana means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Harpaphe haydeniana out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Harpaphe haydeniana in simple terms?

Why does Harpaphe haydeniana matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Harpaphe haydeniana?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Harpaphe haydeniana.