biology

Onykia robusta

Onykia robusta 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 Onykia robusta rather than just read about it. In short: Onykia robusta, also known as the robust clubhook squid and often cited by the older name Moroteuthis robusta, is a species of squid in the family Onychoteuthidae. Reaching a mantle length of 2 m (6.6 ft) it is the largest member of its family and one of the largest of all cephalopods.

Key takeaways

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

Reference excerpt

Onykia robusta, also known as the robust clubhook squid and often cited by the older name Moroteuthis robusta, is a species of squid in the family Onychoteuthidae. Reaching a mantle length of 2 m (6.6 ft) it is the largest member of its family and one of the largest of all cephalopods. The largest specimen with reliable catch data was found in the Bering Sea, a male with a total length of 3.72 m (12.2 ft) and weighing 41.73 kg (92.0 lb). The tentacular clubs are slender, containing 15–18 club hooks. Arms of the species contain 50–60 suckers, and grow to 90–100% of the mantle length. It is found primarily in the boreal to Temperate Northern Pacific.

Size O. robusta can reach up to 2 m (6.6 ft) in mantle length. Nesis gave a maximum mantle length of 2.3 m (7.5 ft), however Roper and Jereb wrote that "this might be in error"; it commonly grows up to 1.6 m (5.2 ft) in mantle length. If the tentacles are measured from the tip to the tip of the mantle, Glaubrecht, M. & M. A. Salcedo-Vargas provided the maximum estimated to be 4–6 m (13–20 ft) in overall length. This species weight is up to 50 kg (110 lb).

Genetic diversity O. robusta has a low genetic diversity, similar to the giant squid Architeuthis dux.

Confusion with Architeuthis

Some time before 1993, a large individual of O. robusta was photographed by Japanese diver Kubota H. in shallow water off southern Japan. In this image, the animal, which appears to be sick or dying, is shown with a diver, although the use of a wide-angle lens exaggerates its size. A video of the same squid appears in a Japanese made-for-television film. The image was published in the 1993 book European Seashells by Guido T. Poppe and Goto Yoshihiro, where it was identified as Architeuthis dux, the giant squid, and said to have been taken in the North Atlantic. If true, this image would represent the earliest known photograph of a live giant squid. In The Search for the Giant Squid (1998), Richard Ellis wrote of this photograph:

"For a moment, I thought that some obscure photograph had captured the most elusive image in natural history. Fortunately for those who have devoted their lives to searching for Architeuthis, this was only an aberration, a case of mistaken identity." More than a decade later, the first photographs of a true live giant squid in the wild were taken, on September 30, 2004.

Illustrations

Worked examples

Example 1 — a first encounter with Onykia robusta

Start with the simplest possible case. Write down what Onykia robusta 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 Onykia robusta 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 Onykia robusta 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 Onykia robusta

In research: Onykia robusta 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 Onykia robusta 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: Onykia robusta is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cephalopods described in 1876, IUCN Red List data deficient species, Molluscs of the Pacific Ocean, so understanding it makes those chapters shorter.
In everyday life: Look for Onykia robusta 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 Onykia robusta in 20 minutes

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

Frequently asked questions

What is Onykia robusta in simple terms?

Why does Onykia robusta 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 Onykia robusta?

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 Onykia robusta.