Machilida

Key takeaways

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

Reference excerpt

Machilida is a suborder of bristletails found on all continents except Antarctica.

Morphology

Overview Machilida are primitive, wingless insects characterized by an elongate, cylindrical body covered with overlapping scales and bearing three terminal filaments (two lateral cerci and a median epiproct). Adults typically range from about 8–20 mm in body length, excluding appendages.

Head The head is hypognathous and large relative to the thorax, with prominent compound eyes that are contiguous medially in most species; ocelli are present and well developed. Antennae are long, multisegmented, and filiform, often exceeding body length.

Mouthparts The mouthparts are ectognathous and adapted for detritivory or algivory, with robust mandibles bearing apical incisors and molar areas, maxillae with 5-segmented palps, and a 3-segmented labial palp.

Thorax The thorax is arched dorsally, especially the meso- and metathorax, giving the body a hump-backed profile. Legs are cursorial and saltatorial: the hind femora are enlarged and muscular, enabling the characteristic jumping behavior; tarsi are 3-segmented with paired claws and an arolium.

Abdomen The abdomen comprises 11 segments. Styli are present on abdominal segments II–IX, and eversible vesicles occur ventrally on segments II–VII, functioning in water uptake and osmoregulation. Dorsal tergites are typically imbricate with posteriorly directed setae; coloration is usually mottled gray, brown, or metallic due to the scale covering. The three caudal filaments are long and many-segmented, usually subequal in length and often exceeding the body.

Sexual dimorphism and nymph stage Sexual dimorphism is subtle. Females possess an external ovipositor formed by paired gonapophyses of segments VIII and IX, typically elongate and annulated; males lack an ovipositor and may have modified parameres associated with the genital opening on segment IX. Nymphs resemble adults in general form but are smaller and sexually immature, with development proceeding through multiple molts and continued post-imaginal molting.

Phylogeny The suborder Machilida was formally proposed in a 2018 phylogenetic study by Zhang et al. based on analyses of morphological and molecular data. The study resolved the long-standing phylogenetic relationships within Archaeognatha, recovering Monura (which contains only the extinct family Dasyleptidae) as the sister group to Machilida. The study confirmed the monophyly of Meinertellidae but suggested that the family Machilidae, as traditionally defined, might be paraphyletic with respect to certain "paleo-type" genera. Fossil evidence from Cretaceous amber (e.g., in Myanmar and Lebanon) indicates that the divergence between the two families is ancient, likely predating the Cretaceous, and suggests a possible Gondwanan origin for Meinertellidae.

Taxonomy

Family Machilidae (Most are restricted to rocky shorelines) Afrochilis Sturm, 2002 Afromachilis Mendes, 1981 Allopsontus Silvestri, 1911 Bachilis Mendes, 1977 Catamachilis Silvestri, 1923 Charimachilis Wygodzinsky, 1939 Coreamachilis Mendes, 1993 Corethromachilis Carpenter, 1916 Coryphophthalmus Verhoeff, 1910 Dilta Strand, 1911 †Gigamachilis Montagna, Haug, Strada, Haug, Felber & Tintori, 2017 Graphitarsus Silvestri, 1908 Haslundichilis Wygodzinsky, 1950 Haslundiella Janetschek, 1954 Heteropsontus Mendes, 1990 Himalayachilis Wygodzinsky, 1952 Janetschekilis Wygodzinsky, 1958 Lepismachilis Verhoeff, 1910 Leptomachilis Sturm, 1991 Machilis Latrielle, 1832 Machilopsis Olfers, 1907 Mendeschilis Gaju, Mora, Molero & Bach, 2000 Mesomachilis Silvestri, 1911 Metagraphitarsus Paclt, 1969 Metamachilis Silvestri, 1936 Meximachilis Wygodzinsky, 1945 Neomachilis Silvestri, 1911 †Onychomachilis Pierce, 1951 Paramachilis Wygodzinsky, 1941 Parapetrobius Mendes, 1980 Pedetontinus Silvestri, 1943 Pedetontoides Mendes, 1981 Pedetontus Silvestri, 1911 Petridiobius Paclt, 1970 Petrobiellus Silvestri, 1943 Petrobius Leach, 1817 Praemachilis Silvestri, 1904 Praemachiloides Janetschek, 1954 Praetrigoniophthalmus Janetschek, 1954 Promesomachilis Silvestri, 1923 Pseudocatamachilis Gaju & Bach, 1991 Pseudomachilanus Paclt, 1969 Silvestrichilis Wygodzinsky, 1950 Silvestrichiloides Mendes, 1990 Stachilis Janetschek, 1957 Trigoniomachilis Stach, 1937 Trigoniophthalmus Verhoeff, 1910 Wygodzinskilis Janetschek, 1954

Family Meinertellidae (Lack scales at base of hind legs and antennae) Hypomachilodes Silvestri, 1911 Machilinus Silvestri, 1905 Machiloides Silvestri, 1904 Meinertellus Silvestri, 1911 Machilontus Silvestri, 1911 Macropsontus Silvestri, 1911 Machilellus Silvestri, 1910 Machilelloides Sturm & Smith, 1993

Distribution and habitat The two families within Machilida have contrasting modern distributions. Machilidae are predominantly found in the Northern Hemisphere, while Meinertellidae are largely distributed across much of the world.

References

Illustrations

Worked examples

Example 1 — a first encounter with Machilida

Start with the simplest possible case. Write down what Machilida claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Machilida 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 Machilida 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 Machilida

In research: Machilida appears in science 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 Machilida 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: Machilida is common in secondary-school and first-year university syllabi. It links to neighbouring topics Archaeognatha, Insect suborders, so understanding it makes those chapters shorter.
In everyday life: Look for Machilida 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.

How to study Machilida in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Machilida 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 Machilida out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Machilida in simple terms?

Machilida is a suborder of bristletails found on all continents except Antarctica. Morphology Overview Machilida are primitive, wingless insects characterized by an elongate, cylindrical body covered with overlapping scales and bearing three terminal filaments (two lateral cerci and a median epipro…

Why does Machilida matter?

Because it connects several science 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 Machilida?

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 Machilida.