science

Tryblidiida

Tryblidiida 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 Tryblidiida rather than just read about it. In short: Tryblidiida is a taxon of monoplacophoran molluscans containing the only extant representatives: 37 species are still alive today, inhabiting the ocean at depths of between 175 and 6,400 metres (574 and 21,000 ft). History of discoveries The first captured living monoplacophoran was Veleropilina zografi in 1896, but at that time it was described as if it were an archaeogastropod, a true limpet, mainly because of its…

Key takeaways

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

Reference excerpt

Tryblidiida is a taxon of monoplacophoran molluscans containing the only extant representatives: 37 species are still alive today, inhabiting the ocean at depths of between 175 and 6,400 metres (574 and 21,000 ft).

History of discoveries The first captured living monoplacophoran was Veleropilina zografi in 1896, but at that time it was described as if it were an archaeogastropod, a true limpet, mainly because of its patelliform (limpet-like) shell. This species was finally revealed to be monoplacophoran 87 years later, in 1983. In April 1952, a living specimen was collected from deep depths in the Middle America Trench off Costa Rica's Pacific coast. In 1957 that species was described and named Neopilina galatheae by its discoverer, Danish biologist Henning Mourier Lemche (1904–1977). An expert in the field has called this discovery "one of the greatest sensations in the [twentieth] century." As of 2008, there were 31 living species known, discovered in waters from 200 meters in depth to hadal depths, or more than 6,000 meters in the deepest ocean trenches. The first specimen photographed alive was Vema hyalina, at a depth of 400 meters off Catalina Island, California, in 1977. Scientists believe that the taxon Monoplacophora is probably polyphyletic and have proposed including all the living members in the order Tryblidiida. In 1989, fossils in Italy from the middle Pleistocene were described which appear to be identical with the living species Micropilina minuta.

Anatomy

Little is known about monoplacophorans. They have a single, flat, rounded bilateral shell that is often thin and fragile; it ranges in size from 3 to 30 millimetres (in recent species). The apex of the shell is at the anterior end. The fossil shells exhibit a series of muscular attachment scars on the inner side, suggesting metamerism; indeed, with living Monoplacophora to study, it can be seen that their body segments exhibit a serial repetition of kidneys, gills and reproductive structure. This used to be interpreted as a true segmentation, which suggested a "missing link" between mollusks and annelids. More recent studies have shown that the repetition of these organs is secondary. Monoplacophorans move on a rounded foot. Their reduced head lacks eyes or tentacles. The mantle cavity forms a horseshoe-shaped groove running around the muscular foot, in a similar fashion to that of the chitons, and contains five or six gills on either side. The mouth opens on the underside between the ends of the groove, while the anus opens into the hindmost part. Like chitons, monoplacophorans possess a sensory subradular organ, as well as a rasping radula. A fold of ciliated tissue surrounds the mouth to the front and sides, while a smaller fold, bearing a number of tentacles, lies just behind it. The stomach contains a style, projecting from a diverticulum, or "style sac". The mouth has a chevron-shaped lip in front of it, and bears tentacles behind it, which have various shapes and layouts in different species. The heart is divided into two equal halves, each with its own auricle, ventricle and aorta. The left and right aorta fuse shortly after leaving the heart, and supply blood to the open circulatory system. There are six pairs of nephridial excretory organs, which empty into the mantle cavity. The nervous system has small ganglia around the oesophagus from which two pairs of main nerve cords run through the body; one pair supplying the foot, and the other the visceral organs. As in the chitons, these main nerve cords are connected by a series of lateral nerves, giving the layout of the nervous system an appearance somewhat like a ladder. There are two pairs of gonads, which release gametes into the water through one of the pairs of nephridia. The sexes are separate, and fertilisation is external.

Ecology

Habitat Monoplacophora are a geographically widespread component of the benthos. Most are known from deep water (1800 – 6500 meters), although several species are found in shallower waters ranging up to 200 meters.

Feeding habits It is presumed that they graze on microscopic organisms in mud or bottom detritus.

Taxonomy of extant species Order Tryblidiida

Family Laevipilinidae Genus Laevipilina J. H. McLean, 1979 Laevipilina antarctica Warén & Hain, 1992 Laevipilina cachuchensis Urgorri, García-Alvarez & Luque, 2005 Laevipilina hyalina J. H. McLean, 1979 Laevipilina rolani Warén & Bouchet, 1990 Laevipilina theresae Schrödl, 2006 Family Micropilinidae Genus Micropilina Warén, 1989 Micropilina arntzi Warén & Hain, 1992 Micropilina minuta Warén, 1989 Micropilina rakiura Marshall, 1998 Micropilina reingi Marshall, 2006 Micropilina tangaroa Marshall, 1992 Micropilina wareni Marshall, 2006 Family Monoplacophoridae Genus Monoplacophorus Moskalev, Starobogatov & Filatova, 1983 Monoplacophorus zenkevitchi Moskalev, Starobogatov & Filatova, 1983 Family Neopilinidae Genus Adenopilina Starobogatov & Moskalev, 1987 Adenopilina adenensis (Tebble, 1967) Genus Neopilina H. Lemche, 1957 Neopilina bruuni Menzies, 1968 Neopilina galatheae Lemche, 1957 Neopilina rebainsi Moskalev, Starobogatov & Filatova, 1983 Neopilina starobogatovi Ivanov & Moskalev, 2007 Genus Rokopella Starobogatov & Moskalev, 1987 Rokopella brummeri Goud & Gittenberger, 1993 Rokopella capulus Marshall, 2006 Rokopella euglypta (Dautzenberg & Fischer, 1897) Rokopella goesi (Warén, 1988) Rokopella oligotropha (Rokop, 1972) Rokopella segonzaci Warén & Bouchet, 2001 Genus Veleropilina Starobogatov & Moskalev, 1987 Veleropilina brummeri (Goud & Gittenberger, 1993) Veleropilina capulus (B. A. Marshall, 2006) Veleropilina euglypta (Dautzenberg & H. Fischer, 1897) Veleropilina goesi (Warén, 1988) Veleropilina oligotropha (Rokop, 1972) Veleropilina reticulata (Seguenza, 1876) Veleropilina segonzaci (Warén & Bouchet, 2001) Veleropilina seisuimaruae Kano, S. Kimura, T. Kimura & Warén, 2012 Veleropilina veleronis (Menzies & Layton, 1963) Veleropilina zografi (Dautzenberg & H. Fischer, 1896) Genus Vema (Clarke & Menzies, 1959) Vema bacescui (Menzies, 1968) Vema ewingi (Clarke & Menzies, 1959) Vema levinae Warén, 1996 Vema occidua B. A. Marshall, 2006

References

Illustrations

Worked examples

Example 1 — a first encounter with Tryblidiida

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

In research: Tryblidiida 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 Tryblidiida 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: Tryblidiida is common in secondary-school and first-year university syllabi. It links to neighbouring topics Mollusc orders, Monoplacophora, so understanding it makes those chapters shorter.
In everyday life: Look for Tryblidiida 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 Tryblidiida in 20 minutes

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

Frequently asked questions

What is Tryblidiida in simple terms?

Why does Tryblidiida 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 Tryblidiida?

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 Tryblidiida.