earth science

Opisthoteuthis chathamensis

Opisthoteuthis chathamensis is a earth 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 Opisthoteuthis chathamensis rather than just read about it. In short: Opisthoteuthis chathamensis, commonly known as the roughy umbrella octopus, is a species of cirrate octopus found in demersal habitats surrounding the Chatham Rise in New Zealand and Macquarie Island (Australian Antarctic Territories). Description Opisthoteuthis chathamensis reaches a maximum length of 18 cm (7.1 in) TL, and a mantle length of 5.4 cm (2.1 in).

Key takeaways

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

Reference excerpt

Opisthoteuthis chathamensis, commonly known as the roughy umbrella octopus, is a species of cirrate octopus found in demersal habitats surrounding the Chatham Rise in New Zealand and Macquarie Island (Australian Antarctic Territories).

Description Opisthoteuthis chathamensis reaches a maximum length of 18 cm (7.1 in) TL, and a mantle length of 5.4 cm (2.1 in). They are described as having subequal arms with around 41-45 suckers in males and 45-55 suckers in females. Their oral surface and the webbing between their tentacles is maroon and the suckers are a pale cream.

Distribution

The type locality of O. chathamensis is near the Chatham Islands at 44°44'S, 77°15'W, 1,180 m (3,870 ft), and was found more broadly around the Chatham Rise, off New Zealand, over a depth range of 900–1,438 metres (2,950–4,720 ft), living on soft sediments.. The species has also more recently been collected from Macquarie Island, to the South West of New Zealand .

Conservation status Opisthoteuthis chathamensis is listed as Critically Endangered by the IUCN due to a 70% decrease in population size in recent years, and has not been seen since 1999, when it was a common bycatch species. In addition, their longevity, low fecundity and slow growth (especially embryonic development which lasts 1.4-2.6 years among other species in the genus) has made them particularly susceptible to population declines and slow recoveries.

References

External links Opisthoteuthis chathamensis discussed on RNZ Critter of the Week, 15 May 2026.

Illustrations

Worked examples

Example 1 — a first encounter with Opisthoteuthis chathamensis

Start with the simplest possible case. Write down what Opisthoteuthis chathamensis claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth 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 Opisthoteuthis chathamensis 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 chathamensis 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 chathamensis

In research: Opisthoteuthis chathamensis appears in earth 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 Opisthoteuthis chathamensis 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 chathamensis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cephalopods described in 1999, Cephalopods of Oceania, Endemic fauna of New Zealand, so understanding it makes those chapters shorter.
In everyday life: Look for Opisthoteuthis chathamensis 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 chathamensis in 20 minutes

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

Frequently asked questions

What is Opisthoteuthis chathamensis in simple terms?

Why does Opisthoteuthis chathamensis matter?

Because it connects several earth 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 Opisthoteuthis chathamensis?

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 chathamensis.