biology

Opisthoteuthis bruuni

Opisthoteuthis bruuni 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 Opisthoteuthis bruuni rather than just read about it. In short: Opisthoteuthis bruuni is a species of finned cirrate octopus found along the western coast of the Americas from Chile to as far north as California. Their tissue is almost jelly-like, and they have short, round bodies.

Key takeaways

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

Reference excerpt

Opisthoteuthis bruuni is a species of finned cirrate octopus found along the western coast of the Americas from Chile to as far north as California. Their tissue is almost jelly-like, and they have short, round bodies. The octopus was named for Anton Bruun, a Danish ichthyologist. The species was originally placed in the genus Grimpoteuthis; however, it was placed in Opisthoteuthis after some re-evaluation. The classification of cirrate octopuses is regularly revised as scientists learn more about these deep-sea octopuses. Recent genetic and molecular testing, for example, confirmed O. bruuni as a member of the family Opisthoteuthidae.

Distribution The species was originally collected off Antofagasta, Chile, at 250 to 360 m depth. Further specimens of O. bruuni have been collected from off Chile and Peru (between 5 and 33 degrees south), over a greater bathymetric range of 250 to 512 m depth. More recently, the species has also been found to occur even further north, off the coasts of California (between Los Angeles and Monterey Bay). Specimens from this region were previously assumed to be an undescribed species informally called Opisthoteuthis "adorabilis" in some news articles, with the late malacologist F.G. "Eric" Hochberg also suspecting this population to be a new species (but he never managed to publish on it), however molecular and morphological data indicates that they are the same species as O. bruuni. When originally described, the extensively gelatinous body and overall form led to the suggestion that O. bruuni is potentially a mid-water or pelagic species. This would be contrary to other Opisthoteuthis which are benthic. However, later research on O. bruuni seems to suggest a benthic habit as material is routinely collected in bottom trawls.

Description & Ecology The species was originally described from a set of 16 juvenile specimens. They were smaller than other known opisthoteuthids, reaching a maximum of 29 mm (1.1 in) mantle length. Even at this small, immature stage, the octopuses displayed sexual dimorphism (sex differences). The males had some enlarged suckers; three enormous suckers on each arm near the mouth were the most prominent, with a small cluster of enlarged suckers also present near the arm tips. This sort of sexual dimorphism is also found in other opisthoteuthids. Further specimens of O. bruuni have been collected from off Chile and Peru (between 5 and 33 degrees south), over a greater bathymetric range of 250 to 512 m depth. This later research also indicates a larger maximum body size (50 mm mantle length, 206 mm total length). Collection of further specimens off of California, indicate the species has a lower sucker count than other members of the family (averaging 35 per arm, maximum of 44) and has a yellow-orange pigmented skin that is easily abraded away during capture in nets. The species is taken as bycatch in trawl fisheries due to its benthic occurrence, and thus may be threatened, but it is currently a data deficient species in the IUCN Red List of threatened species.

References

Worked examples

Example 1 — a first encounter with Opisthoteuthis bruuni

Start with the simplest possible case. Write down what Opisthoteuthis bruuni 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 Opisthoteuthis bruuni 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 Opisthoteuthis bruuni 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 Opisthoteuthis bruuni

In research: Opisthoteuthis bruuni 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 Opisthoteuthis bruuni 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: Opisthoteuthis bruuni is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cephalopods described in 1982, Cephalopods of South America, IUCN Red List data deficient species, so understanding it makes those chapters shorter.
In everyday life: Look for Opisthoteuthis bruuni 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 Opisthoteuthis bruuni in 20 minutes

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

Frequently asked questions

What is Opisthoteuthis bruuni in simple terms?

Why does Opisthoteuthis bruuni 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 Opisthoteuthis bruuni?

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 Opisthoteuthis bruuni.