Koala (Precious Australian arboreal animal)

Koala (Precious Australian arboreal animal)

The koala (scientific name: Phascolarctos cinereus ) is a koala, koala, with fat body, messy and thick hair, and no tail. The adult koala is about 70-80 cm long and weighs about 10 kg. The body is light gray to light yellow. The color around the abdomen is relatively bright. The nose is bare, big and round, the head is round, and the hair on the ears is very fluffy. The forelimbs have very strong claws and are good at climbing. Male koalas weigh more than 50% of females, have a relatively wide face, a pair of relatively small ears, and a large scented thymus. The main second sex feature of a female is her childcare bag, which has 2 teats in it and opens to the rear end.

Koalas spend most of their time on trees, and spend almost their entire lives on eucalyptus trees. Much of the day is spent sleeping, less than 10% of the time is spent on foraging, while the rest of the time is spent on meditation. Koalas almost never drink water. They feed on eucalyptus leaves. They can eat many eucalyptus leaves every day, and they digest well. Distributed in Australia (New South Wales, Queensland, South Australia, Victoria).

Koalas are Australia's national treasures, as well as Australia's peculiar precious primitive arboreal animals.

Ranked 15th in the world's cutest species list by CNN in 2013.  

(Overview reference source: )

name	Koala	Suborder	Koala
Latin name	Phascolarctos cinereus	Section	Koala
nickname	Koala, Koala,Koala,Sloth Bear	Genus	Koala
boundary	animal world	Species	Koala
door	Notochord	subspecies	None
Asia Gate	Vertebrate  subphylum	Namer and year	Goldfuss, 1817
Gang	Mammalia	English name	Koala, Koala bear
Mesh	Kangaroos (double incisors)	Protection level	(IUCN) 2014 ver 3.1-Vulnerable (VU)

Zoology history

Koalas are Australia's national treasures, as well as Australia's peculiar precious primitive arboreal animals. After the Europeans first landed on the mainland of Australia in 1788, John Price became the first European to record such animals as koalas. In 1816, for the first time, koalas had the scientific name " Phascolarctos cinereus ", which means "grey wombat". But when this cute animal became known, people discovered that koalas were not bears at all, and they were far from each other. Ursidae belongs to the order Carnivora, while koalas belong to the order Marsupial. The Koala bear's English name comes from ancient indigenous script, meaning "no drink" (no water). Indigenous people call it "do not drink water" because they can get 90% of the water they need from the eucalyptus they eat and rarely drink water. 

Morphological characteristics

Obese body, messy and thick hair, no tail. The adult koala is about 70-80 cm long and weighs about 10 kg. The body is light gray to light yellow. The color around the abdomen is relatively bright. The nose is bare, big and round, the head is round, and the hair on the ears is very fluffy. The forelimbs have very strong claws and are good at climbing. 

Koalas have a relatively small brain , which may also be an adaptation to their low-energy food. The brain is a high-energy-consuming organ that disproportionately consumes a large portion of the body's entire energy budget. The relative brain volume of the koala is almost the smallest of the marsupials found. The average weight of a koala brain distributed in southern Australia (average weight is 9.6 kg) is only about 17 grams, accounting for only 0.2% of body weight. Relative to its size, the koala's cecum is the longest in all mammals, up to 1.8-2.5 meters long, 3 times its body length or even longer. On each jaw, it has been reduced to 1 premolar and 4 wide and high cusp molars. 

Male koalas weigh more than 50% of females, have a relatively wide face, a pair of relatively small ears, and a large scented thymus. The main second sex feature of a female is her childcare bag, which has 2 teats in it and opens to the rear end. 

The newly born baby koala is only 2 centimeters long and 6 grams in weight, as big as a shelled peanut. They must stay in the mother's nursery bag for 6 months to fully develop. 

Lifestyle

Habits

Koalas spend most of their time on trees, and spend almost their entire lives on eucalyptus trees. Much of the day is spent sleeping, less than 10% of the time is spent on foraging, while the rest of the time is spent on meditation. Koalas will climb trees when they are young. They always fall backward when they go down, buttocks land first and move very slowly. Koalas have made a lot of adaptations to arboreal life. Because they use neither nests nor coverings, their tailless bear-like bodies are covered with a dense layer of hair, which provides good isolation. Most koalas have extremely curved, needle-like toenails on their toes, which makes them extremely superb climbers and can easily climb the smoothest and tallest eucalyptus trees. As they climbed the tree, they grabbed the surface of the trunk with their claws, and used their powerful forearms to move upwards, and at the same time drove the hind limbs upward with a jump. The pincer-like structure of the koala's front paws (the first toe and the second toe are opposite to the other three toes), so that they can hold smaller branches and climb to the outer crown. They are less agile on the ground and often move between trees with four feet walking slowly. They also have childcare bags, but unlike kangaroos, their childcare bags are splayed backwards and there are only two nipples. The paws of koalas can also dig holes. It is the largest digging hole in mammals, up to 10 meters deep, and the diameter of the hole is about 60 cm.  

Koalas are solitary animals, and males who are accustomed to settlement occupy a fixed nesting area. The size of the nest area is related to the richness of the habitat environment. In the southern part of the country where the product is abundant, the range of the nesting area is relatively small. The area occupied by males is 0.015-0.03 square kilometers and the area occupied by females is 0.005-0.01 square kilometers. However, in semi-arid areas, the range of nesting areas is larger Too much, males often occupy 1 square kilometer or more. The nesting area of ​​the dominant males overlaps with that of up to 9 females. Koalas are mainly active at night.  

Feeding habits

Koalas almost never drink water. They feed on eucalyptus leaves. They can eat many eucalyptus leaves every day, and they digest well.  Koala's teeth are suitable for handling eucalyptus leaves. They use molar teeth to chew the leaves into a fine paste, and then these things will be microbial fermentation in the cecum. An adult koala eats about 500 grams of fresh leaves every day. Although there are more than 600 kinds of eucalyptus for koalas to choose from, they only feed on about 30 of them. The degree of partial eclipse varies between populations, and they usually gather on tree species in humid, richer habitats. In southern Australia, where they are distributed, they prefer Eucalyptus multiflorum and Eucalyptus globulus , while the population in the north mainly feeds on the leaves of Eucalyptus globulus, E. globulus , E. globulus, E. variegata, and E. eucalyptus .  

Eucalyptus leaves are not suitable for consumption by most leaf-eating animals (if not completely toxic). Eucalyptus leaves contain very low levels of basic nutrients, including nitrogen and phosphorus, and contain large amounts of structural substances that are difficult to digest, such as cellulose and lignin, and also contain phenolic and terpene (the basic components of oils) , Studies have shown that what is ultimately formed after these substances are combined may be the key to the koala's partial eclipse, because the acceptability of koalas on eucalyptus leaves has been found to be inverse to some highly toxic phenol-terpene mixtures relationship.

Koalas have made a lot of adaptive changes to enable them to cope with such difficult food. Some leaves obviously avoid them completely, and some leaves contain toxins that can be detoxified in the liver and excreted. Processing foods with such low energy levels requires adjustments in behavioral habits, so koalas sleep a lot and can sleep up to 20 hours a day. This has led to a widely circulated statement: they become paralyzed by ingesting compounds in eucalyptus leaves. Koalas also show a high utilization rate of water, except for the hottest season, they can get all the water they need from the leaves. 

Distribution range

Distributed in Australia (New South Wales, Queensland, South Australia, Victoria).

Reproduction

Koalas implement a broad "one male and many female" mating system. In this system, some males occupy most of the mating rights, but the dominant male and the dominant male allocate the mating rights. Accurate details have not been comprehensively and extensively studied, and need to be clearly explained. Female koalas enter sexual maturity when they are 2 years old and begin to breed. Males can also breed at this age, but the mating success rate is usually very low at this time, until they are older (about 4-5 years old) and are large enough to compete successfully with females. Get changed.

In the breeding season, adult males will walk around in a wide range on summer nights. If the male meets another adult male, fighting usually occurs; if the male meets a female in estrus, they may mate. The mating time is very short, generally less than 2 minutes, and is carried out on the tree. Males crawl from behind to females and usually hug it between themselves and the branches when mating.

The female sexual maturity period comes 21-24 months after birth; about 35 days of pregnancy, only one pup is born per fetus, and the child is delivered in the summer (November to March). The cubs live independently after 12 months of birth. Females can reproduce for several years in a row. Up to 18 years. 

Protection status

Protection level

Included in the " IUCN Red List of Endangered Species " (IUCN) 2014 ver 3.1-Vulnerable (VU). 

Endangered cause

Human activities, forest fires and climate change are the main factors that threaten the survival of koalas.  

Population status

The threat to koalas reached its peak in 1924, when more than 2 million koala skins were exported. Until then, the animal had become extinct in southern Australia and largely disappeared from Victoria and New South Wales. The public began to scream for them, the government also issued a hunting ban and strengthened management, this declining trend was reversed. 

Before the British landed in Australia in 1788, the number of Australian koalas exceeded 10 million. However, by 2012, the number of Australian koalas was only about 333,000, including less than 100,000 wild koalas.  

On December 14th, 2009, koalas living in Australia were suffering from extinction. Many of them were suffering from "koala AIDS" (KIDS-koala's immune deficiency syndrome). "Koala HIV" is actually a reversal of filtered virus. The virus destroys the koala's immune system, making them unable to withstand various diseases. The virus spreads through blood contact. There are many koalas in the Duisburg Zoo, but none of them are infected, and the virus only spreads between wild koalas. In the past 6 years, the number of koalas in Australia has dropped sharply from 100,000 to 43,000. If effective measures are not taken in time, koalas are in danger of extinction.  

On June 27, 2012, an Australian koala broke out with a large-scale chlamydia infection, which could be transmitted to humans through direct contact. Due to the sudden increase in the number of chlamydia infections, the number of koalas in the city has dropped sharply by 45% and in rural areas by 15%.  

On November 24, 2019, as forest fires continued to rag in southeastern Australia, the Chairman of the Australian Koala Bear Foundation said that the fires in the past two months destroyed 80% of Koala’s natural habitat, with at least 1,000 koalas. Burying in flames, coupled with a sharp decline in habitat, difficult recovery of burnt forests, and the threat of climate change and disease, the number of koalas in Australia has decreased significantly and is facing functional extinction.