Gracilinanus

Key takeaways

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

Reference excerpt

Gracilinanus is a genus of opossum in the family Didelphidae. It was separated from the genus Marmosa in 1989, and has since had the genera Cryptonanus, Chacodelphys, and Hyladelphys removed from it.

Physical description Gracile mouse opossums, excluding the fat-tailed mouse opossum, in general, have a prehensile tail that is thin and very long. The tails of mouse opossums are naked. Mouse opossums have ears that are, both, large and naked. General opossums, including Gracilinanus species, have noses that are pointed. Another general characteristic that mouse opossum have are mammary glands. Each member of the Gracilinanus species has a dark ring that is found around each eye. The species G. microtarsus has red-brown fur on the top of the body and gray fur on the underside. In comparison with G. microtarsus, G. agilis has paler fur color. Over the years, a new species, G. ignitus, has been added to the genus. G. ignitus has a white patch on its chest. It, as well, has a light, two-tone colored tail that has only a few hairs. The fur color can be used to determine if a member of the genus is part of the G. ignitus species. G. microtarsus, G. emiliae, and G. dryas can be distinguished from G. ignitus by their tails that are only one color. One difference between G. agilis and G. ignitus is that G. agilis has a hairier tail. G. aceramarcae has naked skin compared to G. ignitus. G. emiliae is smaller than G. ignitus. G. emiliae, in general, has a very long tail. A difference between G. emiliae and the rest of the species in the genus is that it has white fur on the underside of the body and the rest of the species have a gray or brown color.

Taxonomy It contains the following species:

Aceramarca gracile opossum (Gracilinanus aceramarcae) Agile gracile opossum (Gracilinanus agilis) Wood sprite gracile opossum (Gracilinanus dryas) Emilia's gracile opossum (Gracilinanus emilae) Northern gracile opossum (Gracilinanus marica) Brazilian gracile opossum (Gracilinanus microtarsus) Peruvian opossum (Gracilinanus peruanus) Cladogram of living Gracilinanus species:

Habitat Gracilinanus species can be found in a number of different places. The different regions that Gracilinanus species can be found are Peru, Bolivia, Brazil, Paraguay, and Venezuela. Some species are found in forests, trees, fallen trunks, tree holes, humid environments, and coffee plantations. G. emiliae is distributed along the Amazonia and the coast of Venezuelan rainforests. G. emiliae is one of the two species in the genus that is found in lowland Amazonian rainforests. G. agilis and G. microtarsus are the only two species that have been found in the central, south, and southeastern parts of Brazil. The other species have been found in the Amazon and not in Brazil. The production of sugar cane and fruits, along with deforestation, is thought to be a reason why the newer species, G. ignitus, has been harder to find.

Endangerment Out of the species that currently exist, only two are on the endangered list. Gracilinanus agilis is not considered to be threatened, in general, but in the specific area of Paraguay, the species is close to being threatened. The only other species that is near threatened is G. dryas. A major threat to these species is that their main habitat is being destroyed by deforestation. However, it has also been reported that these species are on the critically endangered list because they are only known in two general areas where their habitat has been found to be taking a decline. The species of the genus Gracilinanus once occupied other regions in South America but are now extinct there.

Diet The species G. microtarsus has a diet that includes insects, spiders, fruits, termites, beetles and ants. As well, this species has been known to live off of wasps and small invertebrates. However, the main component of G. microtarsus' diet is ants. It is reported that males eat more food than females.

Reproduction Like most marsupials, the female has two vaginas and the males have a two-pronged penis. Some females can have a litter size of up to 15, but usually have a litter of about 7. Females of the species do not have a pouch that the young are able to stay in. For those that do not have a pouch, the young are only attached to the nipples for a short time period and are left in their nests early on in their life.

Interesting facts Some species are nocturnal. A few Gracilinanus species know how to play dead. The newest species that was found, G. ignitus, is reported to be one of the largest of all the species. G. emiliae is one of the species that has only a dozen specimens found. The species in this genus are known to climb a lot and dig holes in trees or the ground.

References

Illustrations

Worked examples

Example 1 — a first encounter with Gracilinanus

Start with the simplest possible case. Write down what Gracilinanus 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 Gracilinanus 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 Gracilinanus 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 Gracilinanus

In research: Gracilinanus 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 Gracilinanus 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: Gracilinanus is common in secondary-school and first-year university syllabi. It links to neighbouring topics Marsupial genera, Opossums, so understanding it makes those chapters shorter.
In everyday life: Look for Gracilinanus 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.

How to study Gracilinanus in 20 minutes

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

Frequently asked questions

What is Gracilinanus in simple terms?

Gracilinanus is a genus of opossum in the family Didelphidae. It was separated from the genus Marmosa in 1989, and has since had the genera Cryptonanus, Chacodelphys, and Hyladelphys removed from it.

Why does Gracilinanus 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 Gracilinanus?

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 Gracilinanus.