biology

Northern wolffish

Northern wolffish 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 Northern wolffish rather than just read about it. In short: The northern wolffish (Anarhichas denticulatus), also known as the blue sea cat or jelly cat, is a species of marine ray-finned fish belonging to the family Anarhichadidae, the wolf fishes. This species is found in the North Atlantic Ocean and Arctic Ocean.

Key takeaways

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

Reference excerpt

The northern wolffish (Anarhichas denticulatus), also known as the blue sea cat or jelly cat, is a species of marine ray-finned fish belonging to the family Anarhichadidae, the wolf fishes. This species is found in the North Atlantic Ocean and Arctic Ocean.

Taxonomy The Northern wolffish was first formally described in 1845 by the Danish zoologist Henrik Nikolai Krøyer with the type locality given as Greenland. The specific name means "denticulated" or "having fine teeth" alluding to the sharper, more finely pointed teeth of this species in comparison to the Atlantic wolffish (A. lupus).

Description

The northern wolffish is a robust, elongate fish with a large head, sharp snout and small eyes. The teeth are distinctive and prominent with large canine-like teeth to the front of the jaws and molar-like teeth at the back of the jaws. It does not have any pelvic fins. The overall colour of the body is greyish to dark brown with a pale purplish sheen and there are frequently marked with many but vague dark bars or spotting. The tissue of the muscles is soft and resembles jelly. The vomerine teeth are large, and may be rounded or pointed and extend back to the line of palatine teeth. The caudal fin is truncate and contains between 18 and 22 fin rays. The maximum published total length is 180 cm (71 in) and the maximum published weight is 20 kg (44 lb).

Distribution and habitat The Northern wolffish is found in the North Atlantic and Arctic oceans where it is distributed in the Barents and Norwegian seas to Spitsbergen, Iceland, Faroe Islands, southern Greenland and south along east coast of North America almost to Cape Cod and west to Prince Patrick Island in the Northwest Territories of Canada. They have been reported from the northern North Sea and the Bay of Biscay. This species inhabits the open areas of the North Atlantic and the offshore region of the continental shelf occurring in bathypelagic waters and has been recorded at a depth of 1,325 m (4,347 ft), the deepest any wolffish has been recorded at, living mainly in the free of the substrate in the water column and occasionally moving up to the surface.

Biology Northern wolffish use large rocks for shelter and nest building. Late in the year, females lay about 46,500 large eggs (up to 8 mm or 5⁄16 inch in diameter) which sink to the sea floor, where they are guarded in nests by the males until they hatch. Growth rates are slow, and they mature at five years or older. Their lifespans are at least 12 years. Unlike other wolffishes, northerns have been found off the bottom during both the juvenile and adult stages. The species does not form large schools or undertake long migrations. This fish feeds in open water on comb jellies and jellyfish, and on bottom-living crustaceans and invertebrates, such as crabs, sea urchins, brittle stars, and starfish.

Conservation status The northern wolffish is protected under the Canadian federal Species at Risk Act (SARA), where it is classified as a Threatened species. A recovery team for the northern and spotted wolffish has almost completed a recovery strategy and plan for both species. The strategy provides a framework for improving the status of wolffish through an enhanced understanding of their life history, potential sources of harm, and implementing management measures such as live release of captured wolffish. The plan also includes habitat stewardship and educational activities designed to involve stakeholders and inform the public. In Europe it is regarded as Endangered because of its sedentary habits, the numbers taken as bycatch by fisheries and the threat of anthropogenic climate change. The IUCN inferred that the northeastern Atlantic population has reduced by over 50% in the last three generations.

Old Woman Fish The Northern wolfish overlaps in range with the Bering wolffish (A. orientalis) in the Bathurst Inlet where the local Inuit do not distinguish between the species, calling both by the name akoak or akoaksaluk ("old woman fish").

References

The Northern Wolffish, a Species at Risk in the North, Department of Fisheries and Oceans, Canada, 2005 Other Text Sources:

Scott and Scott 1988; Quinn 2002 (COSEWIC Status Report); Stock Status Report 2004/031 2003.

External links Media related to Anarhichas denticulatus at Wikimedia Commons For more information, visit the SARA Registry Website at [www.SARAregistry.gc.ca] and the Fisheries and Oceans Canada (DFO) Website.

Illustrations

Worked examples

Example 1 — a first encounter with Northern wolffish

Start with the simplest possible case. Write down what Northern wolffish 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 Northern wolffish 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 Northern wolffish 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 Northern wolffish

In research: Northern wolffish 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 Northern wolffish 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: Northern wolffish is common in secondary-school and first-year university syllabi. It links to neighbouring topics Anarhichas, Endangered fish, Fish described in 1845, so understanding it makes those chapters shorter.
In everyday life: Look for Northern wolffish 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 Northern wolffish in 20 minutes

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

Frequently asked questions

What is Northern wolffish in simple terms?

Why does Northern wolffish 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 Northern wolffish?

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 Northern wolffish.