Koala

The koala is an arboreal herbivorous marsupial native to Australia. It is the only extant representative of the family Phascolarctidae and its closest living relatives are the wombats. The koala is found in coastal areas of the mainland's eastern and southern regions, inhabiting Queensland, New South Wales, Victoria, and South Australia. It is easily recognisable by its stout, tailless body and large head with round, fluffy ears and large, spoon-shaped nose. The koala has a body length of 60–85 cm (24–33 in) and weighs 4–15 kg (9–33 lb). Pelage colour ranges from silver grey to chocolate brown. Koalas from the northern populations are typically smaller and lighter in colour than their counterparts further south. These populations possibly are separate subspecies, but this is disputed.

Koalas typically inhabit open eucalypt woodlands, and the leaves of these trees make up most of their diet. Because this eucalypt diet has limited nutritional and caloric content, koalas are largely sedentary and sleep up to 20 hours a day. They are asocial animals, and bonding exists only between mothers and dependent offspring. Adult males communicate with loud bellows that intimidate rivals and attract mates. Males mark their presence with secretions from scent glands located on their chests. Being marsupials, koalas give birth to underdeveloped young that crawl into their mothers' pouches, where they stay for the first six to seven months of their lives. These young koalas, known as joeys, are fully weaned around a year old. Koalas have few natural predators and parasites, but are threatened by various pathogens, such as Chlamydiaceae bacteria and the koala retrovirus, as well as by bushfires and droughts.

Koalas were hunted by indigenous Australians and depicted in myths and cave art for millennia. The first recorded encounter between a European and a koala was in 1798, and an image of the animal was published in 1810 by naturalist George Perry. Botanist Robert Brown wrote the first detailed scientific description of the koala in 1814, although his work remained unpublished for 180 years. Popular artist John Gould illustrated and described the koala, introducing the species to the general British public. Further details about the animal's biology were revealed in the 19th century by several English scientists. Because of its distinctive appearance, the koala is recognised worldwide as a symbol of Australia. Koalas are listed as of Least Concern by the International Union for Conservation of Nature. The Australian government lists populations in Queensland and New South Wales as Vulnerable. The animal was hunted heavily in the early 20th century for its fur, and large-scale cullings in Queensland resulted in a public outcry that initiated a movement to protect the species. Sanctuaries were established, and translocation efforts moved to new regions koalas whose habitat had become fragmented or reduced. The biggest threat to their existence is habitat destruction caused by agriculture and urbanisation.

The koala is a stocky animal with a large head and vestigial or non-existent tail. It has a body length of 60–85 cm (24–33 in) and a weight of 4–15 kg (9–33 lb), making it among the largest arboreal marsupials. Koalas from Victoria are twice as heavy as those from Queensland. The species is sexually dimorphic, with males 50% larger than females. Males are further distinguished from females by their more curved noses and the presence of chest glands, which are visible as hairless patches. As in most marsupials, the male koala has a bifurcated penis, and the female has two lateral vaginas and two separate uteri. The male's penile sheath contains naturally occurring bacteria that play an important role in fertilisation. The female's pouch opening is tightened by a sphincter that keeps the young from falling out.

The pelage of the koala is thicker and longer on the back, and shorter on the belly. The ears have thick fur on both the inside and outside. The back fur colour varies from light grey to chocolate brown. The belly fur is whitish; on the rump it is dappled whitish, and darker at the back. The koala has the most effective insulating back fur of any marsupial and is highly resilient to wind and rain, while the belly fur can reflect solar radiation. The koala's curved, sharp claws are well adapted for climbing trees. The large forepaws have two opposable digits (the first and second, which are opposable to the other three) that allow them to grasp small branches. On the hindpaws, the second and third digits are fused, a typical condition for members of the Diprotodontia, and the attached claws (which are still separate) are used for grooming. As in humans and other primates, koalas have friction ridges on their paws. The animal has a sturdy skeleton and a short, muscular upper body with proportionately long upper limbs that contribute to its climbing and grasping abilities. Additional climbing strength is achieved with thigh muscles that attach to the shinbone lower than other animals. The koala has a cartilaginous pad at the end of the spine that may make it more comfortable when it perches in the fork of a tree.

Mounted skeleton
The koala has one of the smallest brains in proportion to body weight of any mammal, being 60% smaller than that of a typical diprotodont, weighing only 19.2 g (0.68 oz). The brain's surface is fairly smooth, typical for a "primitive" animal. It occupies only 61% of the cranial cavity and is pressed against the inside surface by cerebrospinal fluid. The function of this relatively large amount of fluid is not known, although one possibility is that it acts as a shock absorber, cushioning the brain if the animal falls from a tree. The koala's small brain size may be an adaptation to the energy restrictions imposed by its diet, which is insufficient to sustain a larger brain. Because of its small brain, the koala has a limited ability to perform complex, unfamiliar behaviours. For example, when presented with plucked leaves on a flat surface, the animal cannot adapt to the change in its normal feeding routine and will not eat the leaves. The koala's olfactory senses are normal, and it is known to sniff the oils of individual branchlets to assess their edibility. Its nose is fairly large and covered in leathery skin. Its round ears provide it with good hearing, and it has a well-developed middle ear. A koala's vision is not well developed, and its relatively small eyes are unusual among marsupials in that the pupils have vertical slits. Koalas make use of a novel vocal organ to produce low-pitched sounds (see social spacing, below). Unlike typical mammalian vocal cords, which are folds in the larynx, these organs are placed in the velum (soft palate) and are called velar vocal cords.

Teeth of a koala, from left to right: molars, premolars (dark), diastema, canines, incisors
The koala has several adaptations for its eucalypt diet, which is of low nutritive value, of high toxicity, and high in dietary fibre. The animal's dentition consists of the incisors and cheek teeth (a single premolar and four molars on each jaw), which are separated by a large gap (a characteristic feature of herbivorous mammals). The incisors are used for grasping leaves, which are then passed to the premolars to be snipped at the petiole before being passed to the highly cusped molars, where they are shredded into small pieces. Koalas may also store food in their cheek pouches before it is ready to be chewed. The partially worn molars of middle-aged koalas are optimal for breaking the leaves into small particles, resulting in more efficient stomach digestion and nutrient absorption in the small intestine, which digests the eucalyptus leaves to provide most of the animal's energy. A koala sometimes regurgitates the food into the mouth to be chewed a second time.

Unlike kangaroos and eucalyptus-eating possums, koalas are hindgut fermenters, and their digestive retention can last for up to 100 hours in the wild, or up to 200 hours in captivity. This is made possible by the extraordinary length of their caecum—200 cm (80 in) long and 10 cm (4 in) in diameter—the largest proportionally of any animal. Koalas can select which food particles to retain for longer fermentation and which to pass through. Large particles typically pass through more quickly, as they would take more time to digest. While the hindgut is proportionally larger in the koala than in other herbivores, only 10% of the animal's energy is obtained from fermentation. Since the koala gains a low amount of energy from its diet, its metabolic rate is half that of a typical mammal, although this can vary between seasons and sexes. The koala conserves water by passing relatively dry faecal pellets high in undigested fibre, and by storing water in the caecum.

Killer whale

The killer whale (Orcinus orca), also referred to as the orca whale or orca, and less commonly as the blackfish or grampus, is a toothed whale belonging to the oceanic dolphin family, of which it is the largest member. Killer whales are found in all oceans, from Arctic and Antarctic regions to tropical seas. Killer whales have a diverse diet, although individual populations often specialize in particular types of prey. Some feed exclusively on fish, while others hunt marine mammals like pinnipeds, and even large whales. They have been known to attack baleen whale calves. Killer whales are regarded as apex predators, lacking natural predators.

Killer whales are highly social; some populations are composed of matrilineal family groups which are the most stable of any animal species. Their sophisticated hunting techniques and vocal behaviours, which are often specific to a particular group and passed across generations, have been anthropomorphically described as manifestations of culture.

The IUCN currently assesses the orca's conservation status as data deficient because of the likelihood that two or more killer whale types are separate species. Some local populations are considered threatened or endangered due to prey depletion, habitat loss, pollution (by PCBs), capture for marine mammal parks, and conflicts with fisheries. In late 2005, the "southern resident" population of killer whales that inhabits British Columbia and Washington state waters were placed on the U.S. Endangered Species list.

Wild killer whales are not considered a threat to humans, but there have been cases of captive orcas killing or injuring their handlers at marine theme parks. Killer whales feature strongly in the mythologies of indigenous cultures, with their reputation ranging from being the souls of humans to merciless killers.

Komodo dragon

The Komodo dragon, also known as the Komodo monitor, is a large species of lizard found in the Indonesian islands of Komodo, Rinca, Flores, Gili Motang, and Padar. A member of the monitor lizard family Varanidae, it is the largest living species of lizard, growing to a maximum length of 3 metres (10 ft) in rare cases and weighing up to approximately 70 kilograms (150 lb). Their unusually large size has been attributed to island gigantism, since no other carnivorous animals fill the niche on the islands where they live. However, recent research suggests the large size of Komodo dragons may be better understood as representative of a relict population of very large varanid lizards that once lived across Indonesia and Australia, most of which, along with other megafauna, died out after the Pleistocene. Fossils very similar to V. komodoensis have been found in Australia dating to greater than 3.8 million years ago, and its body size remained stable on Flores, one of the handful of Indonesian islands where it is currently found, over the last 900,000 years, "a time marked by major faunal turnovers, extinction of the island's megafauna, and the arrival of early hominids by 880 ka ." As a result of their size, these lizards dominate the ecosystems in which they live. Komodo dragons hunt and ambush prey including invertebrates, birds, and mammals. It has been claimed that they have a venomous bite; there are two glands in the lower jaw which secrete several toxic proteins. The biological significance of these proteins is disputed, but the glands have been shown to secrete an anticoagulant. Komodo dragon group behaviour in hunting is exceptional in the reptile world. The diet of big Komodo dragons mainly consists of deer, though they also eat considerable amounts of carrion. Komodo dragons also occasionally attack humans in the area of West Manggarai Regency where they live in Indonesia. Mating begins between May and August, and the eggs are laid in September. About 20 eggs are deposited in abandoned megapode nests or in a self-dug nesting hole. The eggs are incubated for seven to eight months, hatching in April, when insects are most plentiful. Young Komodo dragons are vulnerable and therefore dwell in trees, safe from predators and cannibalistic adults. They take 8 to 9 years to mature, and are estimated to live up to 30 years. Komodo dragons were first recorded by Western scientists in 1910. Their large size and fearsome reputation make them popular zoo exhibits. In the wild, their range has contracted due to human activities, and they are listed as vulnerable by the IUCN. They are protected under Indonesian law, and a national park, Komodo National Park, was founded to aid protection efforts.

Tibetan Mastiff

The Tibetan Mastiff is an ancient breed and type of large Tibetan dog breed (Canis lupus familiaris). Originating with the nomadic cultures of China, India, Mongolia, Nepal andTibet, its use by local tribes of Himachal Pradesh was to protect sheep from wolves, leopards, bears, large mustelids and tigers.

Some breeders differentiate between two "types" of Tibetan Mastiff, the Do-khyi and the Tsang-khyi. The Tsang-khyi (which, to a Tibetan, means only "dog from Tsang") is also referred to as the "monastery" type, described as generally taller, heavier, and more heavily boned, with more facial wrinkling and haw than the Do-khyi or "nomad" type. Both types are often produced in the same litter with the larger, heavier pups being placed in more stationary jobs versus more active jobs for the Tibetan Mastiffs that are better structured and well muscled.

Males can reach heights up to 83 cm (33"). Dogs bred in the West weigh between 45–72 kg (100-160 pounds). The enormous dogs being produced in some Western and some Chinese kennels would have "cost" too much to keep fed to have been useful to nomads; and their questionable structure would have made them less useful as livestock or property guardians.

The Tibetan Mastiff is considered a primitive breed. It typically retains the hardiness which would be required for it to survive in Tibet and the high-altitude Himalayan range, including the northern part of Nepal, India and Bhutan.

Instinctive behaviors including canine pack behavior contributed to the survival of the breed in harsh environments. It is one of the few primitive dog breeds that retains a single estrus per year instead of two, even at much lower altitudes and in much more temperate climates than its native climate. This characteristic is also found in wild canids such as the wolf. Since its estrus usually takes place during late fall, most Tibetan Mastiff puppies are born between December and January.

Its double coat is long, subject to climate, and found in a wide variety of colors, including solid black, black and tan, various shades of "red" (from pale gold to deep red) and bluish-gray (dilute black), often with white markings. Some breeders are now (2014) marketing "white" Tibetan Mastiffs. These dogs are actually very pale "gold", not truly white. Photoshop is often used to make dogs of normal color(s) appear "white" in advertisements.

The coat of a Tibetan Mastiff lacks the unpleasant "big-dog" smell that affects many large breeds. The coat, whatever its length or color(s), should shed dirt and odors. Although the dogs shed somewhat throughout the year, there is generally one great "molt" in late winter or early spring and sometimes another, lesser molt in the late summer or early fall. (Sterilization of the dog may dramatically affect the coat as to texture, density, and shedding pattern.)

Elephants can't jump

Did you know that elephants can't jump?

It is true that adult elephants can’t jump. But there are other animals that can’t either, like sloths, hippos and rhinos. Although, unlike elephants, hippos and rhinos can have all four feet off the ground at the same time when they run.