When it comes to marsupials, the first thing that comes to mind is kangaroos and koalas. In fact , marsupials are a group of animals belonging to the mammalian order Subscendidae ( Posterior Thermos ) . Based on the common feature of having a pouch, they were taxonomically grouped into one order, namely marsupials; now the mainstream classification system divides them into 7 orders: possum, possum, possum, kangaroos, and kangaroos.
Of the approximately 322 species of marsupials that live, many species, mainly possums, are native to South and North America, but more than two-thirds of them are native to Australia and its neighboring islands, dominating the region. Due to the long-term isolation of the animals we are familiar with, the subplacental (euphrasiace) animals have formed many ecological groups equivalent to the placenta: herbivorous, carnivorous, omnivorous, jumping, running, gliding, ground-dwelling, arboreal, burrowing, aquatic, rock-dwelling... This phenomenon allowed marsupials to develop in parallel with placentals from other continents, and many typical examples of convergent evolution emerged.
Interestingly, marsupials Chinese are also mostly named after similar placentals, some of which are very appropriate and some of which are less than satisfactory. So, what are the similarities and differences between the two? Let's understand these wonderful marsupials through the comparison of morphology, ecology, behavior, etc.
opossum
These small to medium-sized nocturnal, omnivorous animals can correspond to placental rodents (rodents), and the two are very similar in terms of body size and relatively long snout, as well as feeding habits. Possums are a large family of about 87 species, with a wide variety of species and ecological types, which are the most primitive species of marsupials, and the most numerous and widely distributed taxa. Its distribution is almost all over South America and most of North America, with the North American possum found in southern Canada and is the northernmost surviving marsupial.
They also differ from rodents in many ways, the biggest of which is that they are mostly arboreal, have no claws on their thumbs, can be held in opposition to other fingers, and have a winding tail, often nesting in tree holes or occupying bird nests. However , there are also species of ground habitats and burrowers similar to rodents. The most peculiar thing is that there is also a kind of webbed-footed possum that adapts to semi-aquatic life, also called the water possum, which has webbing on its hind limbs, similar to the beavers, muskrats, beaver rats, etc. in the rats, but does not eat plants, mainly feeding on crabs, fish, frogs and so on.
In addition, there are two taxa belonging to the order Possum and the order Homolocidae living in South America. The former has 6 species, resembling a shrew with no winding tail, while the latter is tiny, rat-like, with only 1 species.
thylacine
The corresponding placental class of thylacines is the wolf. There is only one species of thylacine, belonging to the order Possum, Thylacine family, and is only native to the australian island of Tasmania. It resembles a wolf, with a pointed mouth, piercing eyes, towering ears that are pointed and wide, and a strong and powerful jaw, making it look as fierce as a wolf. Its body is slightly smaller, equivalent to a small wolf, its body and limbs are relatively thin, and its toe line, standing and running posture are also similar to wolves. It is a terrestrial animal that occupies a similar niche to a wolf, and it moves alone or in pairs at night, hunting a variety of small mammals, medium-sized kangaroos and birds. They are also like wolves when hunting, acting in a mysterious way, and are good at taking long-distance pursuit methods. They do not run fast, but they are endurance and can keep chasing until their prey is exhausted.
There are also many differences between thylacines and wolves. The mouth of the thylacine can be opened very large, can reach 150 ° ~ 180 °; the tail of the thylacine is wide and thin, the root is very thick, the base is wide and thick, gradually sharpened downwards, the tail hair is very small, so it is more like the tail of the kangaroo, and it will not express its emotions with the tail; the thylacine has black-brown horizontal spots on the body, which has obtained the title of "Tasmanian Tiger". It also does not hunt in groups like wolves, always alone or in pairs. In addition, the thylacine can jump like a kangaroo on two hind legs, jumping up to two or three meters in one jump.
Unlike larger predators on other continents, which have lions, tigers, leopards, bears, and other more ferocious predators, the thylacine, which is only 130 centimeters in length, is already the largest predator in modern marsupials. Unfortunately, thylacines have become extinct in the first half of the 20th century due to human hunting, so the new taxonomic system generally does not include thylacines.
Tasmanian devil
The Tasmanian devil is a special member of the Family Tasmanidae and is also native only on the island of Tasmania. Its body length is generally 47 to 83 cm, and it is the largest marsupial carnivore in existence. Similar to placenta-like badgers, Tasmanian devils have a broad and large head, 42 teeth in their large mouths, large ears, small eyes, and a small rough beard on their jaws. They are stout, with short four legs and a thick tail, running rickety and appearing strong and fierce.
Tasmanian devils also occupy a similar ecological niche to badgers, often alone in the dense jungle, day and night, the temperament is very fierce and cruel, when there are small mammals, ground-dwelling birds, lizards, and even wombats to the door, all of them will become their belly. It can also use a lightning raid to kill a kangaroo that weighs 5 times heavier than itself, and the "Tasmanian Devil" is worthy of the name.
Bag shrew
The Tasmanian shrew belongs to the Family Marsupialidae and accounts for about half of the approximately 69 species of Possum ferrets. Unlike other Tasmanian mustelas, such as Tasmanian devils and tasmanian devils, Tasmanian tasmanians are mostly small carnivorous groups. Taking the more typical broad-footed bag shrew as an example, their body length is generally 10 to 14 cm, and the tail length is 12 to 16 cm, which is twice as long as the general shrew with placenta and 4 times longer tail. However, they do look a lot like shrews – round eyes, wide and short ears, pointed snouts, and short white whiskers on the sides of their mouths. They inhabit the primeval forest area below 2800 meters above sea level, nocturnal, digging holes for nests, laying some dry leaves inside, good at climbing trees, mostly feeding on moths, beetles and other insects.
In this taxon, there are two more peculiar members, called kangaroos. They have long tails and large ears, extremely long hind legs, and move like stilts, resembling placenta-like jerboas.
Bag ferret
The species of the bag ferret is more diverse, including the bag ferret, the unke-tailed bag ferret, the Western Australian bag ferret, the forest bag ferret, the striped bag ferret, the long-clawed bag ferret, the Richie bag ferret, the spotted bag ferret, the leather bag ferret, the pygmy bag ferret, etc. They are the most primitive of Australia's marsupials and the most carnivorous of the surviving marsupials. In terms of name alone, they correspond to placental ferrets, and indeed have certain similarities with ferrets in terms of body size, appearance, habits and feeding habits. Most of the marsappers have a short, thick head, an oblong trunk, and short limbs. They are nocturnal animals, sometimes active during the day, and have a fierce temperament. Their incisors are small, their canine teeth are well developed and have sharp incisors, and they have three sharp tips on the molars, indicating that they are carnivores adapted to feed on rodents, insects, etc.
The size of the Possum varies greatly, among them, the spotted Tasmanian mustela is second only to the Tasmanian devil, with a body length of 40 to 75 cm, which is almost twice the size of the weasel (weasel) commonly found in the weasel family, and is the largest surviving carnivorous marsupial in Australia. The smallest, the British pygmy mustela, is only 4.5 cm long, which is 1/3 of the smallest shrew in the ferret family.
Bag food
Ant-beasts
There is only one species of bag anteaters belonging to the family Marsupialidae and Bag Anteaters. It is very similar to anteaters in morphology and habits. It is 17 to 27 cm long and 13 to 17 cm long at the tail, which is only slightly larger than the smallest anteater in the placenta class. Its pointed, long, long, teeth numerous and thin, lined up in long rows, up to 10 cm long, cylindrical, flexible and retractable tongue can reach far to lick termites. They are often solitary during the day, have ground-dwelling, have extremely powerful limbs and claws, and can nest in tree holes, sometimes using rabbit holes or digging holes on their own.
Pocket mole
There are only two species of Tasmanian mole, namely Tasmanian mole and Torre's Marsum, belonging to the Family Marsumidae, which is a small marsupial adapted to underground life, with a body length, shape, habit and fur texture that is very similar to the mole that belongs to the insectivorous class in the placenta.
They inhabit shrub deserts and sandy depressions, and feed mainly on soil animals such as beetle larvae, eggs and earthworms. They are highly adapted to underground excavation life, with completely degenerated eye and outer ear shells, but forelimbs strong and powerful, like shovels. However, although they, like the insectivore mole, can dig exquisite labyrinth-like burrows, they can easily collapse and cannot form permanent tunnels, so they have to constantly walk underground.
Rabbit bag beaver
The possum belongs to the family Possumiaceae, with only two species, namely the small rabbit ear possum and the rabbit ear possum, but the former may have become extinct in the 1950s and the latter is also on the verge of extinction. They are about the size of a rabbit, with a pair of small, round eyes, a pointed, pink snout at the end, and short gray-white whiskers on the sides of the mouth. The pair of long, almost hairless ears in particular make them look reminiscent of rabbits at first glance. However, their tails are much longer than those of rabbits.
The possum inhabits desert areas, is nocturnal, and moves alone. Their forelimbs have 3 fingers, and the claws at the ends of the fingers are thick and long, suitable for digging soil, and they are good at digging spiral-shaped caves. Unlike rabbits, they do not eat grass, but feed on small animals such as insects, spiders, and earthworms.
Possum
Possums usually refer to about 52 species belonging to the kangaroo order possums, honey minks, ring-tailed possums, dwarf possums and possums, including possums, broom-tailed possums, spotted curly-tailed possums, striped possums, tree possums, etc., most of which are similar to sables and pine martens in placenta, with a slightly pointed snout, round ears, and plant fruits, leaves, buds, etc. as the main food, arboreal. The front foot has split toes with large hooked claws, and can flexibly separate five fingers when jumping and grasping branches, stabilizing itself from different angles.
Although the tail hair of possums is thick as a brush, except for the swept-tail possum with a fluffy and hairy tail, the long tails of other species are entangled, and they are often used to hook branches to free up forelimbs to grab food.
Pocket shrew
Australia's sky is not entirely the world of birds, insects and bats, some marsupials can also glide in the air, becoming a group of species developing into the air, the most important of which is the tasmodium, belonging to the kangaroo order, the family Of The Possum, including the Australian Tasmanian shrew, the Ezimus Possum, the yellow-bellied Possum, the Possum, the Possum, the Possum and the Lochsley. Their body shape is very similar to that of rodents, with a wide, mostly hairy membrane on the limbs and body sides, and can glide short distances between trees.
Take the small bag shrew as an example, it is also called the bag shrew, honey bag shrew, is the smallest species in the bag shrew family, the body length of 6 to 8 cm, the head is somewhat mouse-like, the snout is slightly pointed, the end is bare, pink. The eyes are large and round, and the ears are pointed. The tail is almost equal to the length of the body, much like the feathers of a bird, with a soft peduncle in the center and about 8 mm long hairs on the edges of the sides, hence the name feathered pocket shrew. Between the wrists of its forelimbs and the ankles of its hind limbs, there is a membrane similar to the flying membrane of the weasel, also called the pterygium fold. With this membrane and feathery tail, it uses wind or air currents to glide over distances in the air, gliding from one tree to another. Without flying, the membrane contracts and hangs next to the body.
The giant marsupial is much larger than the smaller possum, with a body length of 30 to 48 cm, making it the largest gliding animal in Australia and one of the largest gliders in the world. Like the koala, it feeds only on eucalyptus leaves. It can glide more than 100 meters and can make almost 90° turns. However , it does not belong to the family Possumidae , but to the kangaroo order Ring-tailed Possum family. Another species, the tree-top possum belonging to the kangaroo order possum family, has a body about the size of a small possum, a slightly pointed snout, round ears, round eyes, a membrane between the elbows and knees, a long tail, a wider end, and a patch of pinnate hairs, which can also glide short distances between branches.
It is not surprising that this phenomenon does not belong to the same group of people and has similar habits of life, in rodents, in addition to the squirrel, there are other species of flying squirrels and other groups of species that can glide.
koala
Koalas are the only species belonging to the kangaroo order Koala family and are typical arboreal animals. In appearance, it does not resemble any kind of placenta animal, and it can only be said that it resembles a teddy bear, so it is called a koala. "Koala" is the local name, meaning "animal that does not drink water". It spends most of its time in sleep, similar to the lorises in primates. It feeds mainly on eucalyptus leaves and relies on a large cecum for digestion, which is similar to the langurs, golden snub-nosed monkeys and other animals in primates.
Koalas have shorter hind limbs than their forelimbs, are good at climbing, can grasp branches to climb the edge of eucalyptus trees, can also travel between branches, jump from one branch to another and can also be hung from a branch with one forelimb or one hind limb. Its feet appear large and flattened, with five toes with sharp claws at the ends. The first and second toes of the forefoot and the other three toes are relative, so they can cling to the trunk and branches of the tree and will not fall even if they fall asleep. However, it does not have a meat pad like a dog and a cat on its feet, so it is very difficult to walk on the ground, so koalas rarely go to the ground.
wombat
There are 3 species of wombats belonging to the kangaroo order Wombat family. They are stocky and stocky, and although they look a bit like bears, they are much smaller. In fact, they look more like the short, stout marmots of rodents. Their eyes and ears are small, the tail is degenerate, leaving only traces, the front and back limbs have five toes, not only powerful, but also the claws are very strong, the second and third toes of the hind feet are combined, they are good at digging a complex and wide network of cave passages, living a cave life, hiding in their respective caves during the day to sleep, and only coming out at night.
Wombats feed on the roots, bulbs, bark and fungi of grasses and plants, and its teeth are similar to the teeth of rodents such as marmots, and the upper and lower jaws have two gate teeth that continue to grow like rodents, there is no real tooth root, it grows continuously for life, and it needs to constantly "grind teeth" to maintain a normal state.
kangaroo
Kangaroos are the most famous and representative group of Australian marsupials, belonging to the order of kangaroos in the musk kangaroo family, rat kangaroo family and wallaby family, a total of about 75 species, including long-nosed kangaroos, prairie kangaroos, red brown kangaroos, desert kangaroos, musk kangaroos, rabbit kangaroos, rabbit kangaroos, bush kangaroos, rock kangaroos, rock kangaroos, black-tailed kangaroos, forest kangaroos, jungle kangaroos, wallabies and wallabies.
The smallest and most primitive of these groups is the rat kangaroo, while the medium-sized ones are tree kangaroos, rock kangaroos, rabbit kangaroos, jungle kangaroos, and wallabies. Interestingly, they bear little resemblance to rodents, but occupy ecological niches equivalent to those of even-ungulates such as deer, cattle, sheep or antelopes on other continents. On the one hand, they are basically herbivores, feeding on grass and leaves, etc., with skull morphology adapted to herbivorous life, and the structure and function of their teeth are similar to those of ungulates that lack upper inlet teeth. For example, the lower incisors of the kangaroo are tilted forward, and the lower incisors just match the leathery pad behind the upper incisors when feeding, and this special incisor pattern is suitable for pastoral life. Their digestive system is also similar to that of even ungulates, all of which are fermented in the foregut, and there are a large number of bacteria in the digestive tract to help digest fibrous foods. Some species even have the characteristics of rumination. On the other hand, they developed highly specialized limb structures comparable to those of ungulates and their ability to run fast, suitable for wandering in the grasslands. At high speeds, they jump forward on their feet, their tails act as a balancing organ, reaching speeds of up to 88 km/h, and they can jump up to 13.5 m in one jump and cross obstacles up to 3.3 m high.
Tree kangaroos are the only arboreal type of kangaroo. Apparently, their evolutionary route was to adapt to arboreal life again after adapting to ground habitat life. Although their limbs have gone far in terms of ground-dwelling specialization, arboreals have made many adaptations: forelimb elongation is almost equal to that of the hindlimb, and strong curved claws on the forelimbs and rough soles on the hind feet are beneficial for climbing.
Marsupials originated in the Middle Cretaceous Period of North America (about 100 million years ago), and later with the rise of placental mammals, they were at a disadvantage in survival competition, and disappeared from continents such as Asia, Europe and Africa. Prior to this, the Australian mainland and its nearby islands had been separated from other continents, isolated from the rest of the world, forming a "paradise", floating between the vast Pacific Ocean and the Indian Ocean. Not only are there carnivores in placenta that fail to invade, there are no rivals who compete with them for living space, and the climate and environment have not changed much. As a result, the species here have embarked on a different evolutionary path. Although not as rich as placental species in general, and lacking huge species such as elephants, rhinos, hippos, and giraffes, species that evolved to this day are still thriving and adapted to a variety of lifestyles.