science

Portunus sanguinolentus

Portunus sanguinolentus 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 Portunus sanguinolentus rather than just read about it. In short: Portunus sanguinolentus, the three-spot swimming crab, blood-spotted swimming crab or red-spotted swimming crab, is a large crab found throughout estuaries of the Indian and West Pacific Oceanic countries. Distribution Portunus sanguinolentus is a cosmopolitan species widely distributed across all major waters of the Indo-Pacific; it is found throughout the Red Sea, the Persian Gulf, Mozambique, South Africa, Madaga…

Key takeaways

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

Reference excerpt

Distribution Portunus sanguinolentus is a cosmopolitan species widely distributed across all major waters of the Indo-Pacific; it is found throughout the Red Sea, the Persian Gulf, Mozambique, South Africa, Madagascar, Mauritius, Pakistan, India, Bangladesh, the Maldives, Sri Lanka, the Andaman Islands, Myanmar, the Malay Peninsula, Thailand, Japan, Korea, Taiwan, China, Singapore, Indonesia, the Philippines, Java, Australia, and Hawaii.

Subspecies Two subspecies are recognized:

Portunus (Portunus) sanguinolentus hawaiiensis Stephenson, 1968 Portunus (Portunus) sanguinolentus sanguinolentus (Herbst, 1783)

Description Portunus sanguinolentus is a large crab with a maximum length of 15–20 cm (5.9–7.9 in). Its greyish green carapace is very broad and characterized by 3 red spots in posterior half. A strong spine can be seen on each side. Its swimming legs are flattened and its claws are long.

Ecology Primarily a carnivore, found in marine waters and intertidal zone by juveniles. Inhabits sandy to muddy substrates. It is a harmless crab, but being pinched by its claws can be painful. Commercially harvested as an edible crab species in many countries.

References

External links Media related to Portunus sanguinolentus at Wikimedia Commons

Illustrations

Worked examples

Example 1 — a first encounter with Portunus sanguinolentus

Start with the simplest possible case. Write down what Portunus sanguinolentus 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 Portunus sanguinolentus 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 Portunus sanguinolentus 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 Portunus sanguinolentus

In research: Portunus sanguinolentus 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 Portunus sanguinolentus 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: Portunus sanguinolentus is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cosmopolitan arthropods, Crustaceans described in 1783, Portunoidea, so understanding it makes those chapters shorter.
In everyday life: Look for Portunus sanguinolentus 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 Portunus sanguinolentus in 20 minutes

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

Frequently asked questions

What is Portunus sanguinolentus in simple terms?

Portunus sanguinolentus, the three-spot swimming crab, blood-spotted swimming crab or red-spotted swimming crab, is a large crab found throughout estuaries of the Indian and West Pacific Oceanic countries. Distribution Portunus sanguinolentus is a cosmopolitan species widely distributed across all…

Why does Portunus sanguinolentus 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 Portunus sanguinolentus?

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 Portunus sanguinolentus.