science

Macrouroidei

Macrouroidei 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 Macrouroidei rather than just read about it. In short: Macrouroidei is a suborder of deep sea fish, a diverse and ecologically important group, which are part of the order of cod-like fish, the Gadiformes. The species in the Macrouroidei are characterised by their large heads which normally have a single barbel on the chin, projecting snouts, and slender bodies that taper to whip-like tails, without an obvious caudal fin but what there is of the caudal fin is often conf…

Key takeaways

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

Reference excerpt

Macrouroidei is a suborder of deep sea fish, a diverse and ecologically important group, which are part of the order of cod-like fish, the Gadiformes. The species in the Macrouroidei are characterised by their large heads which normally have a single barbel on the chin, projecting snouts, and slender bodies that taper to whip-like tails, without an obvious caudal fin but what there is of the caudal fin is often confluent with the posterior dorsal and anal fins. There are normally two dorsal fins, the anterior dorsal fin is quite high, the posterior quite low but is longer and takes up a greater proportion of the fish's back. A few species in the Trachyrincidae have a single dorsal fin. The long anal fin is almost as long as the posterior dorsal fin, and sometimes it is longer. The pelvic fin is inserted in the vicinity of the thorax and normally has 5–17 fin rays but these are absent in Macrouroides. The body is covered in small scales and if they have a photophore, it is usually on the midline of the abdomen just in front of the anus. The bioluminescence of these fish is produced by symbiotic bioluminescent bacteria. The structure of the skull has been used to show their placing in the Gadiformes, but they differ from the typical cods in that they possess one stout spine in the anterior dorsal fin. The species in this suborder are mainly benthopelagic, they are found at depths of 200–2000 m, they occur on the sea bed and have a wide distribution from the Arctic to the Antarctic. The species in the Macrouridae normally live near the sea bed on the continental slope, however, some species are bathypelagic or mesopelagic, other species occur on the outer continental shelf. Their bodies are loose in texture rather than firm and they are weak swimmers. Some species are of commercial importance to fisheries.

Families There are ten families within the Macrouroidei:

Family Euclichthyidae Cohen, 1984 (Eucla cods) Family Muraenolepididae Regan, 1903 (eel cods) Family Melanonidae Goode & Bean, 1896 (arrowtails or pelagic cods) Family Trachyrincidae Goode & Bean, 1896 (armoured grenadiers) Family Moridae Moreau, 1881 (codlings or deepsea cods) Family Macruronidae Regan, 1903 (blue grenadiers) Family Lyconidae Günther, 1887 (Atlantic hakes) Family Bathygadidae Jordan & Evermann, 1898 (rattails) Family Steindachneriidae Parr, 1942 (luminous hakes) Family Macrouridae Bonaparte, 1831 (grenadiers or rattails) The earliest known genus is Bobbitichthys Schwarzhans, Milàn & Carnevale, 2021, a stem-macrourid from the middle Paleocene of Denmark. A well-preserved skull of an indeterminate macrourid is known from the Eocene-aged La Meseta Formation of Antarctica. The extinct genus Bolbocara Jordan, 1927 is known from an articulated fossil skeleton from the Late Miocene of California, while Razelaina Carnevale, 2007 is known from the Late Miocene of Algeria.

References

Illustrations

Worked examples

Example 1 — a first encounter with Macrouroidei

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

In research: Macrouroidei 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 Macrouroidei 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: Macrouroidei is common in secondary-school and first-year university syllabi. It links to neighbouring topics Deep sea fish, Fish suborders, Gadiformes, so understanding it makes those chapters shorter.
In everyday life: Look for Macrouroidei 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 Macrouroidei in 20 minutes

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

Frequently asked questions

What is Macrouroidei in simple terms?

Why does Macrouroidei 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 Macrouroidei?

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 Macrouroidei.