earth science

Gigantactis kreffti

Gigantactis kreffti 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 Gigantactis kreffti rather than just read about it. In short: Gigantactis kreffti is a species of marine ray-finned fish belonging to the family Gigantactinidae, the whipnose anglers. This species is found in the deeper waters of the South Atlantic and Western Pacific Oceans.

Key takeaways

Gigantactis kreffti 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 Gigantactis kreffti to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Gigantactis kreffti from memory before moving on to harder problems.

Reference excerpt

Gigantactis kreffti is a species of marine ray-finned fish belonging to the family Gigantactinidae, the whipnose anglers. This species is found in the deeper waters of the South Atlantic and Western Pacific Oceans.

Taxonomy Gigantactis krefftii was first formally described in 1981 by Erik Bertelsen, Theodore W. Pietsch and Robert J. Lavenberg with its type locality given as the South Atlantic at 39°19'S, 3°15'W, Walther Herwig station 406/71, from a depth of 0–2,000 m (0–6,562 ft). This species is placed within the genus Gigantactis, which the 5th edition of Fishes of the World classifies within the family Gigantactinidae, a family within the suborder Ceratioidei, the deep sea anglerfishes of the order Lophiiformes, the anglerfishes.

Etymology Gigantactis kreffti is a member of the genus Giganactis, the name of which is a combination of gigantos, meaning "giant", with actis, which means "ray", an allusion to the unusually long illicium of the genus's type species, G. vanhoeffeni. The specific name honours the German ichthyologist Gerhard Krefft of the Institute for Sea Fisheries in Hamburg, recognising his contribution to the knowledge of the fauna of the deep seas.

Description Gigantactis kreffti is known only from metamorphosed females. These are elongated anglerfishes with an elongate caudal peduncle and a relatively short illicium, which is no greater than 120% of the standard length of the fish. The esca is pear-shaped, rounder in younger females, and rather spiny. The esca has short filaments near its tip and no filaments on its base. The teeth in the upper jaw are arranged in one series with few teeth on the sides of the jaw; there are 4 or 5 series of long teeth in the lower jaw. The caudal fin is relatively short, covered in skin, and with rays that have a length equivalent to 30% of the standard length. This species has a maximum published standard length of 25.2 cm (9.9 in).

Distribution and habitat Gigantactis kreffti has been recorded from 4 widely scattered localities, two in the southwestern Atlantic off South Africa and two in the Western Pacific, one off Tasmania and one off Japan. It has been collected from depths between 1,000 and 2,000 m (3,300 and 6,600 ft).

References

Further reading Stewart, A.L. and Pietsch, T.W. 2015. Family Gigantactinidae. In: Roberts, C., Stewart, A.L. and Struthers, C.D. (eds), The Fishes of New Zealand, pp. 932–936. Te Papa Press.

Worked examples

Example 1 — a first encounter with Gigantactis kreffti

Start with the simplest possible case. Write down what Gigantactis kreffti 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 Gigantactis kreffti 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 Gigantactis kreffti 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 Gigantactis kreffti

In research: Gigantactis kreffti 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 Gigantactis kreffti 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: Gigantactis kreffti is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bioluminescent fish, Deep sea fish, Fish described in 1981, so understanding it makes those chapters shorter.
In everyday life: Look for Gigantactis kreffti 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 Gigantactis kreffti in 20 minutes

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

Frequently asked questions

What is Gigantactis kreffti in simple terms?

Why does Gigantactis kreffti 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 Gigantactis kreffti?

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 Gigantactis kreffti.