science

Mermithidae

Mermithidae is a science 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 Mermithidae rather than just read about it. In short: Mermithidae is a family of nematode worms that are endoparasites in arthropods. As early as 1877, Mermithidae was listed as one of nine subdivisions of the Nematoidea.

Key takeaways

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

Reference excerpt

Mermithidae is a family of nematode worms that are endoparasites in arthropods. As early as 1877, Mermithidae was listed as one of nine subdivisions of the Nematoidea. Mermithidae are confused with the horsehair worms of the phylum Nematomorpha that have a similar life history and appearance. Mermithids are parasites, mainly of arthropods. Most are known from insects, but some are recorded from spiders, scorpions and crustaceans. A few are known to parasitize earthworms, leeches and molluscs, and a specimen is known from a spider preserved in Baltic amber. At least 25 species are known to parasitize mosquito larvae, making them of considerable interest in biological control. A species, probably Pheromermis vesparum, was recorded from the invasive Asian hornet (Vespa velutina) in France. The parasite was considered to be a member of the local fauna which had adapted to a new host. However, the authors concluded that the mermithid could not hamper the hornet invasion nor be used in biological control programs against this invasive species.

Life history

Mermithids are wire-like and have a smooth cuticle with layers of spiral fibres. The digestive tract is similar to that of free-living nematodes only in the young larvae prior to their parasitic life; in the parasitic stages the oesophagus is disconnected from the mid-intestine, and females lack an anus. The female genital opening is at the midbody, while the male opening is at the tip and visible as one or two spicules. The eggs are laid either in water or on land, and the newly hatched larvae are free-living, as are the adults that emerge from the hosts to lay eggs. The taxonomy of the group has been confused due to poor specimen collection as well as very limited morphological characteristics, and most are discovered by entomologists rather than nematologists. Even the best-studied species, Romanomermis culicivorax, has an unclear taxonomic status.

Host behavior alteration Mermithid nematodes alter their host's hemolymph osmolality (concentration of salt) to induce water-seeking behavior.

Association with iridoviruses

Mermithids have been found to be associated with iridoviruses in several arthropod species. Strelkomermis spiculatus have been found to transmit an iridovirus in the mosquito species Culex pipiens, Culex apinicus, and Aedes aegypti. Isopod iridescent virus has been found associated with Thaumamermis cosgrovei in the isopod species Porcellio scaber and Armadillidium vulgare. An unidentified iridovirus virus has been found in the fly species Culicoides variipennis sonorensis in association with Heleidomermis magnapapula infections. In all three instances, iridoviral infections occurred at a much higher rate in mermithid-parasitized individuals. However, in the case of the interaction between C. v. sonorensis, H. magnapapula, and their iridovirus, the virus appears to kill both host and parasite before they reach maturity, impairing the mermithid's biological control of C. v. sonorensis.

Included genera These genera are included in the family:

Abathymermis Rubtsov, 1871 Aranimermis Bathymermis Daday, 1911 †Cretacimermis Poinar, 2001 Eumermis Daday, 1911 Gastromermis Micoletzky, 1923 †Heydenius Taylor, 1935 Hydromermis Corti, 1902 Lanceimermis Artyukhovskii, 1969 Limnomermis Daday, 1911 Mermis Dujardin, 1842 Pheromermis Poinar, Lane & Thomas, 1976 Quadrimermis Coman, 1961 Reesimermis Tsai & Grundman, 1969 Romanomermis Spiculimermis Artyukhovskii, 1963 Strelkovimermis Rubzov, 1969 Tetramermis Steiner, 1925

References

External links Nickle, WR (1972). "A Contribution to our Knowledge of the Mermithidae (Nematoda)". Journal of Nematology. 4 (2): 113–46. PMC 2619923. PMID 19319257. Biological control potential https://web.archive.org/web/20081214081804/http://flnem.ifas.ufl.edu/HISTORY/entomophilic_history.htm https://web.archive.org/web/20091014110925/http://www.uel.ac.uk/mosquito/issue10/mermithids.htm Mermis nigrescens on the UF / IFAS Featured Creatures Web site

Illustrations

Worked examples

Example 1 — a first encounter with Mermithidae

Start with the simplest possible case. Write down what Mermithidae 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 Mermithidae 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 Mermithidae 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 Mermithidae

In research: Mermithidae 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 Mermithidae 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: Mermithidae is common in secondary-school and first-year university syllabi. It links to neighbouring topics Endoparasites, Mermithidae, Mind-altering parasites, so understanding it makes those chapters shorter.
In everyday life: Look for Mermithidae 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 Mermithidae in 20 minutes

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

Frequently asked questions

What is Mermithidae in simple terms?

Mermithidae is a family of nematode worms that are endoparasites in arthropods. As early as 1877, Mermithidae was listed as one of nine subdivisions of the Nematoidea.

Why does Mermithidae 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 Mermithidae?

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 Mermithidae.