biology

Myleusnema bicornis

Myleusnema bicornis 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 Myleusnema bicornis rather than just read about it. In short: Myleusnema bicornis is an intestinal parasite of Myleus ternetzi, or "Ternetz's Silver Dollar", a freshwater Characoid fish commonly found in the French Guiana river. M. bicornis has several unusual morphological characteristics, namely the two postcloacal "horns" in the posterior of males, and a separate elongated cephalic region (head) that may be extended and retracted.

Key takeaways

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

Reference excerpt

Myleusnema bicornis is an intestinal parasite of Myleus ternetzi, or "Ternetz's Silver Dollar", a freshwater Characoid fish commonly found in the French Guiana river. M. bicornis has several unusual morphological characteristics, namely the two postcloacal "horns" in the posterior of males, and a separate elongated cephalic region (head) that may be extended and retracted. These features differ vastly from other Cosmocercoidean nematodes, as well as any others within the family Kathlaniidae, and as such necessitate the creation of the new genus Myleusnema; however, no genetic taxonomic studies have been performed.

Etymology The generic name derives from the Greek terms Myleus (generic name of fish host) and nema (short for nematode), whereas the specific name, bicornis, refers to the two postcloacal "horns" present on males.

Morphology Myleusnema bicornis possess characteristics which are common for all nematodes: they are long and cylindrical with a "worm-like" shape, show bilateral symmetry, and contain a pseudocoelom, a primitive body cavity. Only longitudinal muscles are present within nematodes, which are covered by a protective cuticle layer. Nerve chords relay stimuli from sensory organs such as amphids, phasmids, cephalic papillae, and caudal papillae. M. bicornis differs from other nematodes in that it possess an extended oesophageal cavity, a ventral pre-anal sucker, and an unusual number of caudal papillae (12 total, 1 lone). The cephalic extremity is also made up of three lips and lamella-like formations. The combination of these features taxonomically place the organism into the family Kathlaniidae. M. bicornis has the ability to extend or retract its cephalic region, though the specific function of this ability is unknown. Its caudal papillae are unique in both number and distribution: 10 subventral pairs and 2 lateral pairs, along with one unpaired papillae in front of the cloaca. Sexual dimorphism is also present in Myleusnema bicornis, in the form of two postloacal "horns" present on males.

Footnotes

References 1. Jégu, M. 2003 Serrasalminae (Pacus and piranhas). p. 182-196. In: R.E. Reis, S.O. Kullander and C.J. Ferraris, Jr. (eds.) Checklist of the Freshwater Fishes of South and Central America. Porto Alegre: EDIPUCRS, Brasil. http://fishbase.org/Summary/speciesSummary.php?ID=28031&genusname=Myleus&speciesname=ternetzi. 2. Moravec, F. and Thatcher, V.E. 1996. Myleusnema bicornis gen. et sp. n. (Nematoda: Kathlaniidae), an intestinal parasite of a freshwater serrasalmid fish, Myleus ternetzi, from French Guiana. Folia Parasitologica 43:53-59. 3. Roberts, L., J. Janovy. 2000. Foundations of Parasitology. US: The McGraw Hill Companies, Inc.. Fetterer, R., M. Rhoads. 1996, 375-377p.

Worked examples

Example 1 — a first encounter with Myleusnema bicornis

Start with the simplest possible case. Write down what Myleusnema bicornis 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 Myleusnema bicornis 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 Myleusnema bicornis 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 Myleusnema bicornis

In research: Myleusnema bicornis 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 Myleusnema bicornis 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: Myleusnema bicornis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Nematodes described in 1996, Parasitic diseases, Parasitic nematodes of fish, so understanding it makes those chapters shorter.
In everyday life: Look for Myleusnema bicornis 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 Myleusnema bicornis in 20 minutes

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

Frequently asked questions

What is Myleusnema bicornis in simple terms?

Why does Myleusnema bicornis 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 Myleusnema bicornis?

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 Myleusnema bicornis.