biology

Raja straeleni

Raja straeleni 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 Raja straeleni rather than just read about it. In short: Raja straeleni, the biscuit skate, false thornback skate, or spotted skate, is a species of marine fish in the skate family (family Rajidae) of order Rajiformes. It is native to the eastern Atlantic Ocean.

Key takeaways

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

Reference excerpt

Raja straeleni, the biscuit skate, false thornback skate, or spotted skate, is a species of marine fish in the skate family (family Rajidae) of order Rajiformes. It is native to the eastern Atlantic Ocean.

Description This skate has a blunt, angular snout, a long, thick tail, and a broad flattened angular disc with wing-like pectoral fins. They reach a disc width of up to 68 cm (27 in) and are a light brown in colour with black spots, whorls and rosettes. The pectoral fins also have a dark brown eye spot near the base, although these are absent in juveniles. The upper side of the body is covered in many thornlike spines, with a row of strong thorns along the back and down the tail. Larger individuals may also have thorns on the white underside.

Distribution and habitat This species is found in the eastern Atlantic, from Rio de Oro in Western Sahara to South Africa. It is an oceanodromous marine demersal species. It is found from areas close inshore to a depth of 800 m (2,600 ft), although they are most common at depths of 100–300 m (330–980 ft). They prefer sandy areas and are found in shallow enclosed bays and on the continental slope.

Ecology

Behaviour This skate migrates towards the coastal shallows during the warm season and towards deep waters in winter. They spend most of their time lying flat on the sand, where they are well camouflaged.

Diet This skate feeds on invertebrates, including crustaceans, bony fishes and fish offal.

Reproduction This species is oviparous: The egg cases are dark brown and have horn-like projections on the shell.

Etymology Raja: Latin, raja, -ae = a sting ray; straeleni: Named after V. Van Straelen, director of IRSNB, Belgium.

Importance to humans This species is caught by commercial fisheries and as a gamefish. It is caught by shore and ski-boat anglers and by hake trawlers. The pectoral fins sold as 'skate wings'.

Conservation This species is classified as being near threatened by the IUCN. While population data in South Africa seem to indicate that the population is stable in the region, there is intense unmanaged fishing in the northern parts of its range. This, coupled with the deceased landings and the fishery range expansions that have stemmed from depleting fish stocks, suggests that it has declined massively in parts of its range due to exploitation This is exasperated by its slow rate of reproduction.

References

"Raja straeleni". Integrated Taxonomic Information System. 19 March 2014.

External links Media related to Raja straeleni at Wikimedia Commons

Illustrations

Worked examples

Example 1 — a first encounter with Raja straeleni

Start with the simplest possible case. Write down what Raja straeleni 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 Raja straeleni 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 Raja straeleni 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 Raja straeleni

In research: Raja straeleni 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 Raja straeleni 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: Raja straeleni is common in secondary-school and first-year university syllabi. It links to neighbouring topics Fish described in 1951, Fish of the East Atlantic, IUCN Red List near threatened species, so understanding it makes those chapters shorter.
In everyday life: Look for Raja straeleni 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 Raja straeleni in 20 minutes

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

Frequently asked questions

What is Raja straeleni in simple terms?

Why does Raja straeleni 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 Raja straeleni?

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 Raja straeleni.