“7th grade Reptiles” - Performed by a student of 7th “A” class of Malik Kurmashev. Don't you like snakes? Missouri, USA The sense organs are better adapted to the terrestrial way of life. . Squad: turtles. A detachment of aquatic reptiles live in rivers, lakes and swamps. The ribs and chest are developed. The modern representative is hatteria.
"Mushrooms Biology" - The Riddle. Fruit body. Proverbs and sayings. Plants. White mushroom. Sprinkle the resulting fossa with leaves and needles. - Serve as animal feed, mushroom picking rules. The structure of the cap mushroom. - Some mushrooms are a medicine for animals and humans. 1. Carefully twist the mushroom. Theme of the lesson: Boletus. Leg.
"Arthropod structure" - Class Arachnids (subclasses: Haymakers, Scorpions, Ticks, Spiders). Tarantulas. Orbiting spiders. Wolf spider Presentation for grade 7. General characteristic of the type. Taxonomy type. Crustacean class (subclasses Lower and Higher or Decapods). Banana spiders. Horse spiders. Type Arthropods. More than 1.5 million species, 2/3 of all types of living creatures. Sidewalk spiders. Haymaker Spider. Crab spider
“Mammals Grade 7” - Detachment Insectivores. Squad One-pass. Hedgehog eared. Colony of water nights. In bats, during hibernation, the temperature drops to +1 - +5 degrees. Yes, I really ....... The mole is ordinary. You recognized me? Nightlights are an ancient, morphologically primitive group of animals. Primates. In winter they hibernate.
"Lesson Reproduction of organisms" - Moon fish. Amoeba division. Termitnik. Propagation of fish. Cartilaginous fish: stingray, shark. Teacher: Bobyleva N.P. We learn what the biological role of various methods of reproduction and fertilization in nature is. Lesson objectives We will learn to compare different types of reproduction and fertilization. Malaria parasite in blood cells. Crushing eggs of vertebrates. Reproduction of hepatic trematode. Lesson summary.
Currently, ovipositing, or single-pass, is the only detachment of the subclass cloacal class mammals of the chordate type. The second name of this order is the first animals, since these animals, along with marsupials, are the most primitive of all modern mammals. The name of the order is due to the presence of characteristic features in all animals of this group. Single pass have a cesspool formed by the fusion of the final sections of the intestine and the genitourinary system. Similarly, representatives of amphibians, reptiles and birds have cesspools. Also, all first animals lay eggs, and the hatching cubs are fed by females with milk.
Scientists believe that in the process of evolution, the oviparous descended from reptiles as a side branch from the line of mammals to the appearance of marsupial and placental species. The structure of the skeleton of the limbs, skull, circulatory system, sensory organs of ovipositing and reptiles is similar. The fossilized remains of the first animals were found in the strata of the Mesozoic era of the Jurassic or Late Cretaceous. Initially, egg-laying appeared in Australia, and later they spread to South America and Antarctica. But so far, single-pass animals have been preserved only in Australia and on nearby islands (Tasmania, New Guinea).
The ovipositor order is divided into two families (platypus and echidna), including six species. Oviparous animals of small sizes (30-70 cm). The physique is dense, limbs stop-moving, adapted for digging or swimming. Just like reptiles, first animals have no placenta. The mammary glands in oviparous mammals are devoid of nipples. And numerous small ducts open directly on the animal’s stomach in special paired glandular fields. Cubs simply lick milk from these sites on mother's skin.The intestines and urogenital sinus in oviparous fall into the cloaca. The brain of the first beasts is simple enough. The cerebral cortex does not have convolutions. First animals are considered warm-blooded animals. But despite the presence of hair, the body temperature of the egg-laying is relatively low, and can vary significantly (from 25 to 35 degrees) depending on fluctuations in ambient temperature.
Echidna (2 species) and prochidina (3 species) are terrestrial burrowing animals that live in burrows. They feed on invertebrate animals, which are extracted from the soil, from under the stones. Echidna limbs have long claws to dig the ground. The body is covered with stiff needles (modified hair). The female usually lays one egg, which she carries in a skin bag on the ventral side until it matures.
Unlike echidna, the platypus leads a semi-aquatic lifestyle. These animals are covered with thick, hard coat, which practically does not get wet in the water. The eardrum on the limbs promotes rapid swimming. Characteristic is the presence of horn covers on the jaws, which resemble an anser beak. Hence the name of the class. The platypus feeds on invertebrate animals, filtering the water with its beak. Platypus nests are arranged in burrows, where one or two eggs are laid and hatched. Echidna are believed to be secondary terrestrial mammals, separated from ancient aquatic animals - platypuses.
Oviparous - mammals belong to the class, subclass cloacal. Among all known vertebrates, single-pass mammals are the most primitive. The detachment was named due to the presence of representatives of a special characteristic. Oviparous have not yet adapted to live birth and lay eggs for reproduction, and after the babies are born, they are fed milk.
Biologists believe that monotremes emerged from reptiles as an offshoot of a group of mammals, even before the birth of marsupials and placental animals.
The platypus is a representative of the egg-laying
The structure of the skeleton of the limbs, the head, organs of the circulatory system, respiration of primitive animals and reptiles is similar. The fossils of the Mesozoic era reveal the remains of oviparous. Single pass then populated the territory of Australia, and later occupied the South American expanses and Antarctica.
To date, the first animals can be found only in Australia and the islands located nearby.
The origin and diversity of mammals. Oviparous and real animals.
The ancestors of mammals are reptiles of the Paleozoic. This fact confirms the similarity in the structure of reptiles and mammals, especially at the stages of embryogenesis.
In the Permian period a group of theriodonts, the ancestors of modern mammals, was formed. Their teeth were placed in the recesses of the jaw. Most animals had bone palate.
Nevertheless, environmental conditions that formed during the Mesozoic era contributed to the development of reptiles and they became the dominant group of animals. But the climate of the Mesozoic soon changed dramatically and reptiles failed to adapt to new conditions, and mammals occupied the main niche of the animal world.
The class of mammals is divided into 2 subclasses:
- First Beast Subclass or Single Pass,
- subclass Real animals.
These animals and one-pass are united by a number of signs: hairy or needle-like outer cover, mammary glands, hard palate. First animals also have common characteristics with reptiles and birds: the presence of cloaca, laying of eggs, a similar structure of the skeleton.
Single Pass Detachment - General Description
Oviparous - small animals with a flattened torso, short limbs with large claws and a leathery beak. They have small eyes, a short tail. The ovipositor does not have an external auricle.
Only the representatives of the platypus family have teeth and they look like flat plates equipped with protrusions along the edge.The stomach is intended only for storing food, the intestines are responsible for the digestion of food. The salivary glands are very developed, large, the stomach passes into the cecum, which, together with the urogenital sinus, flows into the cloaca.
First animals have no real uterus and placenta. Reproduction by laying eggs, a little yolk in them, and the shell includes keratin. The mammary glands have many ducts that open on the ventral side in special glandular fields, since there are no nipples in single pass.
Body temperature can vary: it does not rise above 36 ° C, but with significant cooling it can drop to 25 ° C. Echidna and platypuses do not make sounds, since they are devoid of vocal cords. The life span of the echidna is about 30 years, the platypus is about 10. They inhabit forests, steppes with shrubs and even occur in mountainous areas (at an altitude of up to 2500 m.).
Representatives of the oviparous have poisonous glands. A bone spur is located on the hind limbs, through which a toxic secret flows. The poison is potent, in many animals it provokes a malfunction of vital organs, it is also dangerous for humans - it causes severe pain and extensive swelling at the site of the lesion.
Catching and hunting for representatives of the squad is prohibited, as they are listed in the Red Book due to the threat of extinction.
Platypus and echidna
The platypus and echidna are egg-laying, mammals, the only representatives of the order.
A small animal is about 30-40 cm long (body), the tail is up to 15 cm, weighing 2 kg. Males are always larger than females. It lives near ponds.
Five-fingered limbs are well suited for digging land; on the coast, platypuses dig holes for themselves about 10 meters in length, equipping them for later life (one entrance is underwater, the other a couple of meters above water level). The head is equipped with a beak, like a duck (hence the name of the animal).
Platypuses for 10 hours are in the water where they get food: aquatic vegetation, worms, crustaceans and mollusks. The swimming membranes between the fingers on the forelegs (on the hind limbs are almost not developed) allow the platypus to swim well and quickly. When an animal dives under water, its eyes and ear openings close, however, the platypus can navigate in the water thanks to the sensitive nerve endings on its beak. He even has an electroreception.
The platypuses bear their babies for a month and give one to three eggs in the offspring. First, the female incubates them for 10 days, and then about 4 months she feeds with milk and at the age of 5 months the platypuses, already capable of independent life, leave the hole.
Oviparous mammals also include echidna , found in forests, in appearance similar to a hedgehog. To obtain food, the echidna digs the earth with powerful claws and with the help of a long and sticky tongue receives the necessary food (termites, ants).
The body is covered with thorns, which protect it from predators, when approaching danger, the echidna curls up and becomes inaccessible to enemies. The female weighs about 5 kg, and lays an egg with a weight of 2 g. The echidna hides the egg in a bag formed by a leathery fold in the abdominal region and wears it, heating it with its warmth, for two weeks. A newborn baby is born with a mass of 0.5 g, continues to live in the mother’s bag, where it is fed with milk.
After 1.5 months, the echidna leaves the bag, but continues to live in a hole under the protection of her mother. After 7-8 months, the baby is already able to find food itself and differs from the adult only in size.
Question 1. Why can we say that oviparous, marsupials and insectivores are very ancient and most primitive mammals?
Oviparous are ancient mammals that have a number of primitive signs characteristic of reptiles, from which they originate. Their body temperature is unstable (from 22 to 25 ° C in the platypus or 30 ° C in the echidna).They reproduce by laying eggs that are hatched (platypus) or hatched in a leather bag on the belly (echidna). The eggs are covered with cornified shells resembling the shell of reptile eggs.
Marsupials already bear cubs inside the body, but for a very short time (which is connected with the primitive device compared with higher mammals, their breeding systems). Cubs are born underdeveloped. Their further development proceeds in the bag.
Insectivores are also considered ancient and rather primitive mammals, since they are able to hibernate (a characteristic feature of cold-blooded reptiles), they are quite small in size, their dental apparatus consists of a large number of teeth (for example, 36 have hedgehogs), which have the same structure. and other primitive signs.
Question 2. Why are oviparous and marsupials preserved mainly in Australia and adjacent islands?
Australia lost touch with other continents when more advanced mammalian groups had not yet appeared there. Therefore, the marsupials remained the highest and most prosperous group of the mammalian class on this continent, which somewhat pushed aside the egg-laying, but continued their joint existence.
Question 3. Why is it necessary to protect rare egg-laying, marsupial, insectivorous and bats?
These mammalian orders are very ancient and have many primitive traits that negatively affect the survival of these animals in competitive habitat conditions. Therefore, a person should take over their protection.
31. Class Mammals, or Beasts. Squads: One-pass, Marsupials, Insectivores, Bats
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Everyone knows from the school program on mammals. Do you know that an oviparous mammal is a separate animal species that lives only on the territory of one continent - Australia? Let's look at this particular kind of animal in more detail.
For a long time, the existence of unique animals that breed, hatching eggs, was not known. The first report of these creatures came to Europe in the 17th century. At this time, a skin of a marvelous creature with a beak covered with wool was brought from Australia. It was a platypus. Alcoholic copy was brought only after 100 years. The fact is that platypuses practically do not tolerate captivity. It is very difficult for them to create conditions during transportation. Therefore, they were observed only in the natural environment.
Following the discovery of the platypus, news came of another creature with a beak, only now it is covered with needles. This is echidna. For a long time, scientists argued about which class to classify these two creatures. And they came to the conclusion that the platypus and the echidna should be taken out in a separate detachment. So the unit appeared One-pass, or cloacal.
A unique creature leading a nocturnal lifestyle. Platypus is common only in Australia and Tasmania. The animal lives half in the water, that is, it builds holes with access to water and on land, also feeds in water. The creature is small - up to 40 centimeters. It has, as already mentioned, a duck nose, but at the same time it is soft and covered with skin. Only in appearance is very similar to duck. There is also a 15-centimeter tail, similar to the tail of a beaver. The paws have membranes, but they do not interfere with the platypus walking on the ground and digging holes perfectly.
Since the genitourinary system and intestines exit in the animal through one hole, or cloaca, it was attributed to a separate species - Cloacaceous.Interestingly, the platypus swims, unlike ordinary mammals, with the front paws, and the hind legs serve as a helm. Among other things, let's pay attention to how it multiplies.
An interesting fact: before breeding, the animals fall into a 10-day hibernation, and only after that the mating season begins. It lasts almost all autumn, from August to November. Platypuses mate in water, and after a two-week period, the female lays an average of 2 eggs. Males do not participate in the future life of offspring.
The female builds a special hole (up to 15 meters long) with a nest at the end of the tunnel. Lines it with raw leaves and stems to maintain a certain humidity so that the eggs do not dry out. Interestingly, for protection, she also builds a 15-centimeter-thick barrier wall.
Only after preparatory work does she lay eggs in the nest. The platypus hatches eggs, curled up around them. After 10 days, babies are born, naked and blind, like all mammals. The female feeds the babies with milk, which flows from the pores directly through the wool into the grooves and accumulates in them. Toddlers lick milk and thus feed. Feeding lasts about 4 months, and then the kids learn to get their own food. It was the breeding method that gave this species the name "egg-laying mammal."
Echidna is also an egg-laying mammal. This is a land creature of small size, reaching up to 40 centimeters. It also lives in Australia, Tasmania and the islands of New Guinea. In appearance, this animal looks like a hedgehog, but with a long narrow beak, not exceeding 7.5 centimeters. Interestingly, the echidna has no teeth, and she catches prey with a long sticky tongue.
The body of the echidna is covered on the back and sides with thorns that are formed from coarse wool. The coat covers the stomach, the head and legs are fully adapted for a certain type of food. She feasts on termites, ants and small insects. She leads a daily lifestyle, although finding it is not easy. The fact is that it has a low body temperature, up to 32 degrees, and this does not allow it to suffer a decrease or increase in ambient temperature. In this case, the echidna becomes lethargic and rests under the trees or hibernates.
The method of reproduction of echidna
Echidna is an egg-laying mammal, but it was only possible to prove this at the beginning of the XXI century. Interesting mating games echidnas. There are up to 10 males per female. When she decides she is ready to mate, she lies on her back. At the same time, the males dig a trench around her and begin the struggle for primacy. The one who is stronger copulates with the female.
Pregnancy lasts up to 28 days and ends with the appearance of one egg, which the female moves to the brood fold. It is still not clear how the female moves the egg into the bag, but after 10 days the baby appears. A baby comes into the world not fully formed.
The birth of such a baby is very similar to the birth of young marsupial animals. They also undergo final development in the mother’s bag and leave it as adults, ready for independent life. Interesting fact: marsupials are also common only in Australia.
How does the baby echidna appear? He is blind and naked, his hind limbs are not developed, his eyes are covered with a leathery film, and fingers are formed only on the front paws. To get to the milk, the baby needs 4 hours. It is interesting that in the bag the mother has 100-150 pores that secrete milk through special hairs. The kid only needs to get to them.
The baby is in the mother’s bag for about 2 months. He gains weight very quickly through nutritious milk. Echidna milk is the only one that has a pink color due to the large amount of iron in it. Feeding lasts up to 6.5 months. After young growth learns to get food on their own.
Passage is another ovipositing mammal. This creature is much larger than its counterparts. The habitat is the north of New Guinea and the islands of Indonesia. The projidina’s dimensions are impressive, up to 80 centimeters, and its weight is up to 10 kilograms. In appearance, it looks like a echidna, but the beak is much longer, and the needles are much shorter. She lives in mountainous areas and feeds mainly on worms. The structure of the oral cavity is interesting: the tongue has teeth, and with it it can not only chew food, but, as has been noticed, even turn stones over.
This species is the most poorly studied, as it lives in the mountains. But it was noted that the animal does not lose mobility in any weather, does not hibernate and is able to regulate the temperature of its own body. Reproduction of oviparous mammals, which include prochidna, occurs in the same way as in the other two species. She displays only one egg, which is placed in a bag on her stomach, and feeds the cub with milk.
Now let's look at the species of mammals that live on the Australian continent. So, what is the difference between egg-laying, marsupial and placental mammals? First you need to say that all mammals feed their offspring with milk. But the birth of babies has huge differences.
Oviparous animals have one thing in common. They lay eggs like birds, and hatch them for a certain time. After the appearance of the offspring, the mother's body produces milk, which the babies eat. It should be noted that the cubs do not suck milk, but lick it from the grooves on the female’s stomach. The absence of nipples distinguishes the egg-laying from other mammals.
They have a brood bag, hence their name. The bag is located on the stomach of females. Having reached her, a newborn baby finds a nipple and, as it were, hangs on it. The fact is that babies are born unformed and spend a few months in their mother’s bag until they are fully developed. It must be said that ovipositing and marsupial mammals in this respect have similarities. Toddlers are echidna and prokhidny also born underdeveloped and placed in a kind of brood fold.
And what about placental mammals? They have babies born fully formed due to the presence of the placenta in the uterus. Due to it, the process of nutrition and development of the cub occurs. The bulk of the animals belongs to the placental.
Here is such a diversity of species exists on one continent.
Predatory marsupials are considered the most primitive in the detachment. In most species, the brood bag is not too well developed, for example, appears exclusively during the breeding season of the marsupial marten, and has the appearance of a normal skin fold in the Tasmanian devil. Marsupial predators usually live alone, in the steppes, forests, deserts and even mountains up to 4000 meters high. As the name implies, they feed on insects or meat of other animals. A significant part of predatory marsupials prefers to walk on the ground, however, some of them have succeeded quite well in moving around trees.
The names of many marsupials are identical to the names of their placental relatives living outside of Australia. The reason for this is the rather strong similarity both in the appearance of these animals and in their lifestyle. So, the marsupial marten moves remarkably through the trees - just like its American and European namesakes. Both ordinary and marsupial jerboas live in deserts and jump on well-developed hind legs. Marsupial mice are also very similar to ordinary mice, but unlike rodents, marsupial jerboas and mice eat insects and small animals, and not grass at all.
Placental and marsupial animals are the result of different evolutionary paths and, despite a rather strong external similarity, have very strong differences.
The order of marsupials consists of more than 250 species of animals, which are very different from each other both in appearance and in lifestyle. What unites them is that their cubs are born underdeveloped, and their mother carries them for a while in a special brood bag. The order of marsupials includes herbivores - koalas, kangaroos, and insectivorous nambats and marsupial moles, and predatory Tasmanian devils.
Like oviparous, marsupials are not ancestors of the placental. Marsupials are much more organized than oviparous, they give birth to living, albeit underdeveloped, cubs, and do not lay eggs. The body temperature of the egg-laying is lower than that of marsupials, but the latter still do not have a constant body temperature akin to placental animals.
Oviparous, like other mammals, are descended from reptiles, however, they separated from them quite early, forming their own branch of development. This subclass is represented by a single detachment called single pass, which in turn combines two families: echidna and platypus. These are the most primitive of all living mammals that do not even have nipples - cubs lick milk that is secreted from the tubular glands, right from the mother’s hair. These unique animals have a number of other features - they are quite poisonous, have a special cesspool, in which both the bladder and intestines open. In addition, platypuses and echidna are voiceless and toothless. These original animals inhabit the forest, steppes with bushes and mountains up to 2500 m high.
A small group of the most primitive of the living mammals. Single pass females lay 1 or 2, rarely 3 eggs of the telolecital type (characterized by a high content of yolk, the main mass of which is placed at one of the poles of the egg). Hatching of calves from eggs takes place with the help of a special egg “tooth”, which is formed on a small egg-bone (os carunculae). Young animals hatched from eggs are fed with milk. During the breeding season, a brood bag may form on the female’s abdomen, in which the deferred matures. The sizes of one-pass are small: body length is 30 - 80 cm. The head is small, with an elongated "beak" covered with a cornea. The eyes are small, the outer auricles are barely visible or absent altogether. The body is covered with coarse hair and spikes or soft thick fur. Vibrissas are absent. In the calcaneal region of the hind limbs there is a horny spur, especially strongly developed in males. The spur is pierced by a canal - a special duct connected with the so-called shin gland, whose function is not entirely clear. Apparently, it has some significance in reproduction. It is also suggested (unconvincing) that the secretion of the lower leg is toxic and the spur serves as a defense weapon. The mammary glands are tubular. There are no real nipples and the excretory ducts of the glands open separately from each other on two glandular fields of the female’s belly.
The skull is flattened. The front section is elongated. The cartilaginous skull and the ratio of bones in the roof of the skull are to some extent similar to reptiles. The roof of the skull with frontal and posterior bones, the presence of these bones in the roof of the skull is the only case among mammals. The drum bone has the appearance of a flattened ring, not fused with the skull. Bone auditory meatus is absent. The malleus and the anvil in the middle ear are fused together and have a long process (processus folii). The lacrimal bone is absent. The zygomatic bone is greatly reduced in size or absent. Only monotremes among all mammals have a praevomer. The intermaxillary bone has a process similar to that of the reptile (processus ascendus), this is the only case among mammals. The articular fossa for the lower jaw is formed by a scaly bone.The lower jaw with only two weakly expressed processes - coronary and angular.
Teeth are present only in young animals or are completely absent. The shape of the teeth to a certain extent resembles the shape of the teeth of the Mesozoic Microleptidae. The skeletal zones of the forelimbs are characterized by unique mammalian coracoid (coracoideum) and procoracoid (procoracoi-deum). In the presence of these bones, the similarity of the shoulder girdle of single pass with the shoulder girdle of reptiles is manifested. Sternum with a large pectoralis (episternum). The collarbone is very large. Shoulder without comb. The humerus is short and powerful. The ulna is much longer than the radius. The wrist is short and wide. The front and hind limbs are five-fingered. Fingers end with claws. In the pelvic girdle of males and females there are so-called marsupial bones (ossa marsupialia), attached to the pubic. Their function is unclear. The symphysis of the pelvic bones is very elongated. The proximal tibia with a large flattened process (peronecranon). The vertebral column consists of 7 cervical, 15-17 thoracic, 2-3 lumbar, 2 sacral, 0-2 coccygeal and 11-20 caudal vertebrae. The whole body is covered with a highly developed layer of subcutaneous muscle (rap-niculus carnosus). Only in the area of the head, tail, extremities, cloaca and mammary glands, the subcutaneous musculature is not developed. The lower jaw has musculus detrahens, attached on its inner side, this is the only case in mammals. The larynx is primitive and does not have vocal cords.
The brain is generally large, has the structural features of a mammal, but retains a number of reptile signs. Large hemispheres with numerous, sometimes small furrows. The structure of the cerebral cortex is primitive. The olfactory shares are very large. The cerebellum is only partially covered by the cerebral hemispheres. The corpus callosum is absent; it is presented only in the form of commissura dorsalis. Strongly developed sense of smell. Jacobson organ is well developed. The structure of the hearing organs is primitive. Eyes with or without blinking membrane. The sclera has cartilage. The vascular membrane is thin. Musculus dilatatorius and Musculus ciliaris are absent. The retina has no vessels.
The salivary glands are small or large. The stomach is simple, without digestive glands, which is the only case in mammals. Its function, apparently, is to store food similarly to the function of bird goiter. The digestive tract is divided into small, large intestines, there is a cecum. The intestine opens into the cesspool, which is present in both sexes. The liver is multi-lobed, with a gall bladder. The single-pass heart has a structure characteristic of mammals, but it also retains some reptile-like signs, for example, that the right atrioventricular opening is equipped with only one valve.
The average body temperature is lower than that of other mammals (platypus on average 32.2 ° C, echidna - 31.1 ° C). Body temperature can vary between 25 ° and 36 ° C. The bladder, into which the ureters flow, opens into the cloaca. Oviducts fall into the cloaca separately (there is no vagina or uterus). Testes are located in the abdominal cavity. Penis is mounted on the ventral wall of the cesspool and serves only for excretion of sperm.
Single pass live in forests of various types, in the steppes overgrown with shrubs, on the plains and in the mountains, rising to 2.5 thousand meters above sea level. They lead a semi-aquatic (platypus) or terrestrial (echidna) way of life, activity is twilight and nocturnal, feed on insects and aquatic invertebrates. Life expectancy up to 30 years. Distributed in Australia, Tasmania, New Guinea. There are 2 families in the detachment: echidnus - Tachyglossidae Gill, 1872 platypuses - Ornithorhynchidae Burnett, 1830. Modern monotremes in their characteristics are closest to reptiles in comparison with all other modern mammals. However, they are not the ancestors of marsupial or placental mammals, but represent a separate specialized branch in the evolution of mammals.
The fossil remains of members of the monotreme unit are known only from Australia. The most ancient finds date from the Pleistocene and do not significantly differ from modern forms. There are two possible theories explaining the origin of single pass. According to one of them, monotremes developed independently and in complete isolation from other mammals, starting from the early period of the appearance of mammals, possibly from their reptilian ancestors. According to another theory, the one-pass group was isolated from the ancient marsupials and acquired its features thanks to specialization, while retaining a number of features characteristic of marsupials, it underwent degeneration and, possibly, to a certain extent, returned to the forms of ancestors (reversion). The first of the theories seems more plausible. Significant differences in morphology between echidna and platypus arose over a relatively short period of time - starting from the Upper Eocene. Echidnae are secondarily terrestrial mammals, separated from ancient aquatic platypuses (Gregory, 1947).
2 families: platypus and echidna
Range: Australia, Tasmania, New Guinea
Food: insects, small aquatic animals
Body length: 30 to 80 cm
Subclass egg laying mammals represented by only one detachment - single pass. This detachment unites only two families: platypus and echidna. Single pass - the most primitive of the living mammals. They are the only mammals that, like birds or reptiles, breed, laying eggs. Oviparous women feed their young with milk and therefore are classified as mammals. Female echidnas and platypuses have no nipples, and the young lick the milk secreted by the tubular mammary glands directly from the hair on the mother’s belly.
Echidna and Platypus - The most unusual representatives of the class of mammals. They are called single-pass, because both the intestines and the bladder of these animals open in one special cavity - the cloaca. Two oviducts in single-pass females also go there. Most mammals do not have cloaca, this cavity is characteristic of reptiles. The egg-laying stomach is also amazing - it, like a bird's goiter, does not digest food, but only stores it. Digestion occurs in the intestines. These strange mammals even have a lower body temperature than others: without rising above 36 ° C, it can drop to 25 ° C depending on the environment, like in reptiles. Echidna and platypus are voiceless - they have no vocal cords, and only young platypuses have toothless decaying teeth.
Echidna live up to 30 years, platypuses live up to 10. They live in forests, steppes overgrown with shrubs, and even in mountains at an altitude of up to 2500 m.
The origin and discovery of oviparous
Platypuses and echidna are poisonous mammals. On their hind legs, they have a bone spur along which toxic liquid flows. This poison causes death in most animals, and in humans - severe pain and swelling. Among mammals, except for the platypus and echidna, only the representative of the order of insectivores — the crabfish and two species of shrews — are poisonous.
Like all mammals, ovipositors are descended from reptilian ancestors. However, they separated quite early from other mammals, choosing their own path of development and forming a separate branch in the evolution of animals. Thus, the egg-laying were not the ancestors of other mammals - they developed in parallel with them and independently of them. Platypuses are more ancient animals than the echidna that descended from them, mutated and adapted to the terrestrial way of life.
Europeans learned about the existence of oviparous almost 100 years after the discovery of Australia, at the end of the 17th century. When the skin of the platypus was brought to the English zoologist George Shaw, he decided that he was just played, the Europeans were so unusual for the appearance of this bizarre creation of nature.And the fact that the echidna and the platypus breed by laying eggs has become one of the greatest zoological sensations.
Despite the fact that the echidna and platypus have long been known to science, these amazing animals still present new discoveries to zoologists.
Miracle beast platypus as if assembled from parts of different animals: his nose, like a duck beak, his flat tail with a shovel was taken from a beaver, the webbed feet are similar to flippers, but equipped with powerful claws for digging (when digging, the membrane bends, and when walking, it folds, without interfering with free movement). But with all the seeming absurdity, this beast is perfectly adapted to the lifestyle that it leads, and has not changed much over millions of years.
The platypus at night preys on small crustaceans, mollusks and other small aquatic animals. The fin-tail and webbed feet help him to dive and swim perfectly. The eyes, ears and nostrils of the platypus in the water close tightly, and he finds his prey in the dark under water with the help of a sensitive “beak”. On this leathery “beak” there are electroreceptors capable of picking up weak electrical impulses emitted when moving by aquatic invertebrates. Responding to these signals, the platypus immediately searches for prey, stuffs cheek pouches, and then on the shore eats up what has been caught.
All day the platypus sleeps near a reservoir in a hole dug by powerful claws. There are dozens of such holes in a platypus, and each has several exits and entrances - not an extra precaution. To breed offspring, the female platypus prepares a special hole lined with soft leaves and grass - it is warm and humid there.
Pregnancy lasts a month, and the female lays from one to three leathery eggs. The platypus mother hatches eggs for 10 days, warming them with her body. Tiny new-born platypuses, 2.5 cm long, live for another 4 months with their mother on their belly, eating milk. The female spends most of the time lying on her back and only occasionally leaves the hole to feed herself. When leaving, the platypus walled up the cubs in a nest so that no one would disturb them until she returned. At 5 months of age, the mature platypuses become independent and leave the maternal hole.
Platypuses were mercilessly killed because of valuable fur, but now, fortunately, they are taken under the strictest protection, and their numbers have increased again.
A relative of the platypus, she is not at all like him. She, like the platypus, swims perfectly, but she does it only for pleasure: she does not know how to dive and get food under water.
Another important difference: the echidna has brood bag - pocket on the belly where she places the egg. Although the female grows her cubs in a comfortable hole, she can safely leave her - an egg or a newborn cub in her pocket is reliably protected from the vicissitudes of fate. At the age of 50 days, the little echidna already leaves the bag, but for another 5 months she lives in a hole under the auspices of a caring mother.
Echidna lives on the earth and feeds on insects, mainly ants and termites. Raking termite mounds with strong paws with hard claws, she removes insects with a long and sticky tongue. The body of the echidna is protected by needles, and in case of danger, it turns into a ball, like an ordinary hedgehog, substituting a prickly back for the enemy.
From May to September, the echidna begins the mating season. At this time, the female echidna enjoys the special attention of males. They line up and go after her in one file. The procession is led by a female, and grooms follow her in seniority - the youngest and most inexperienced close the chain. So, as a company, echidna spend a whole month, together looking for food, travel and relax.
But for a long time the rivals cannot coexist peacefully. Demonstrating their strength and passion, they begin to lead a round dance around the chosen one, raking the earth with their claws. The female is in the center of the circle formed by a deep furrow, and the males begin to fight, pushing each other out of the ring-shaped pit. The winner of the tournament gets the favor of the female.
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The name is due to the fact that the intestine and urogenital sinus enter the cloaca (similarly in amphibians, reptiles and birds), and do not go outside in separate passages.
Modern single pass
- platypus family (Ornithorhynchidae )
- Platypus (Ornithorhynchus anatinus )
- family Echidaceae (Tachyglossidae )
- Directions (Zaglossus )
- Burton's Passage ( Zaglossus bartoni )
- Bruyne's Passage (Zaglossus bruijni )
- Attenborough Drive (Zaglossus attenboroughi )
- Echidna (Tachyglossus )
- Australian Echidna (Tachyglossus aculeatus )
- Directions (Zaglossus )
Fossils single pass
Reported single-pass fossils are relatively rare. Although biochemical and anatomical evidence suggests that single-pass deviated from the mammalian line to the origin of marsupial and placental mammals, only a handful of single-pass fossils are known before the Miocene. Few existing Mesozoic fossils, such as the genus Steropodon (Steropodon ), presumably indicate that monotremes first developed in Australia during the Upper Jurassic or Lower Cretaceous. Subsequently, they spread to both South America and Antarctica, which were then still united with Australia, but probably did not survive on any continent for a long time. Most likely single-pass nursing groups are considered Henosferida from deposits of the Middle-Late Jurassic period of Western Gondwana. Both groups showed an advanced pretribosphenic structure of the lower molars with a probable absence of a protocone on the upper teeth and a plesiomorphic preservation of the postdental bones and the “false-angle” process of the lower jaw. Also common for these two groups are the dentition with three molars and the position of the Meckel groove, which extends ventrally to the mandibular foramen. In single passes during further evolution, a “mammalian” middle ear with three auditory ossicles was formed, as in theriium mammals and multituberculates.
All species listed in this section are known only by fossils.
- Family Kollikodontidae
- Kind Kollikodon
- Kollikodon ritchiei Ancient one-pass, 100-105 million years.
- Kind Kollikodon
- Family Steropodontidae May be part of the Platypus, close relatives of the modern platypus.
- Kind Steropodon
- Kind Teinolophos
- Teinolophos trusleri 123 million years is the oldest single pass instance.
- Platypus family (Ornithorhynchidae )
- Genus Obdurodon Includes several platypuses of the Miocene era (5-24 million years).
- Monotrematum sudamericanum Age 61 million years. (Originally placed in a separate genus, now moved to Obdurodon )
- Genus Obdurodon Includes several platypuses of the Miocene era (5-24 million years).
- Echidna Family (Tachyglossidae )
- Rod Proechidna (Zaglossus ) Upper Pleistocene (0.1-1.8 million years ago).
- Kind Megalibgwilia
- Megalibgwilia ramsayi Late Pleistocene
- Megalibgwilia robusta Miocene
Single passage passage
Returning to the guard, Petya found Denisov in the hallway. Denisov in excitement, anxiety and frustration at himself that let Petya go, was waiting for him.
- Thank God! He shouted. - Well, thank God! - he repeated, listening to Petit's enthusiastic story. “And why didn’t you take you because of you!” Said Denisov. “Well, thank God, now go to bed.” Another scream "eat to utg" a.
“Yes ... No,” said Petya. “I don't feel like sleeping yet.” Yes, I know myself, if I fall asleep, it's all over. And then I got used to not sleeping before the battle.
Petya sat for some time in the hut, joyfully recalling the details of his trip and vividly imagining what will happen tomorrow. Then, noticing that Denisov fell asleep, he got up and went to the yard.
It was still completely dark in the yard. The rain passed, but drops still fell from the trees. Near the guardhouse were black figures of Cossack huts and horses tied together. Behind the hut two wagons with horses stood blackened, and a burning fire blushed in the ravine. Cossacks and hussars did not all sleep: in some places they were heard, along with the sound of falling drops and the close sound of chewing horses, quiet, as if whispering voices.
Petya came out of the canopy, looked around in the dark and went to the wagons. Someone was snoring under the wagons, and around them stood, chewing oats, saddled horses.In the dark, Petya recognized his horse, which he called Karabakh, although it was a Little Russian horse, and approached it.
“Well, Karabakh, we will serve tomorrow,” he said, sniffing her nostrils and kissing her.
- What, master, do not sleep? - said the Cossack, who was sitting under the wagon.
- No, but ... Likhachev, it seems, to call you? After all, I just arrived. We went to the French. - And Petya told the Cossack in detail not only his trip, but also why he went and why he believes that it is better to risk his life than to make Lazar at random.
“Well, they would have sucked,” said the Cossack.
“No, I'm used to it,” answered Petya. - And what, do you have flints in your pistols? I brought with me. Is it necessary? You take it.
The Cossack leaned out from under the wagons to take a closer look at Petya.
“Because I'm used to doing everything carefully,” said Petya. - Others so, somehow, will not be prepared, then they regret. I do not like that.
“That's for sure,” said the Cossack.
First Beast Subclass Overview
First beasts (Prototheria) - a subclass of primitive mammals that combine features mammals, reptiles and birds. In this subclass, the only non-dead infraclass is distinguished. cloacalopposed to infraclasses placental and marsupials from subclass animals. Modern types of primitive animals form only one detachment - single pass. First Beasts are a small group of species common in the Australian region.
According to a number of signs, the subclass of the primordial animals and the infraclass cloacal are considered the most archaic and primitive among the infraclasses of mammals. Unlike other mammals, the first animals reproduce by laying eggs, however, more than half of the period of development of the embryo passes through the female genital tract. Thus, the laid eggs contain an already sufficiently developed embryo, and we can talk not only about egg laying, but also incomplete live births.
In females, instead of nipples, there are areas of the mammary glands from which the offspring lick the milk. Fleshy lips (effective when sucking) no. In female echidnas, only the left half of the reproductive apparatus functions (as in birds). In addition, they, like birds and reptiles, have only one passage.
There is wool, however, homoothermia (maintaining body temperature at a constant level) is incomplete, body temperature varies from 22–37 ° С.
Nowadays, all species of cloaca live in Australia, New Guinea and Tasmania. In total, there are four species of cloacal in two families (platypuses and echidna) and one single detachment (single-pass).
Curiously, the appearance of the first dinosaurs - archosaurs, at one time, was marked by a massive (but not complete) extinction terapsid, the higher forms of which in their organization were very close to single-pass mammals, and according to some assumptions, may have had mammary glands and hair.
The first mammals appeared about 220 million years ago. These were triconodonts, which include, in a number of opinions, extinct mammals megazostrodon, gobiconodon, repenom, joholdens and etc.
Triconodonts (lat. Triconodonta) have no descendants among modern mammals. They lived in the Triassic, Jurassic and Cretaceous periods. Their name (lit. “tooth with three cones”) is based on the characteristic shape of the teeth (not to be confused with another infraclass or subclass - three-tuberous!).
Most likely, they led a nocturnal lifestyle, hiding from predatory dinosaurs, and ate small reptiles and insects. But some triconodonts were able to hunt small dinosaurs (like repenom) The ecological niche previously occupied by the triconodonts was occupied by the displacing them rodents.
- Triconodonts on Wikipedia. Here are assigned to triconodonts amphilestids, eutriconodonts, gobiconodonts, repenomas.
How are single pass different from other mammals?
Single pass differs from others in that they have a common opening (like, and) for the urinary, digestive and reproductive systems, which is called cesspool.
They lay their eggs, and like other mammals, they are capable of lactation (the production of milk by females to feed cubs). But instead of nipples, as in other mammals, single-pass secrete milk from the mammary gland through large pores in the skin on the stomach.
Monotremes are mammals. They have a low breeding rate. Parents take care of their cubs for a long time before they become independent.
The fact that they are single pass is not considered the only factor that distinguishes them from other mammalian orders. They have unique teeth that are believed to have developed independently of the teeth of placental and marsupial mammals. Monotremes also have an additional set of bones in the shoulder (episternum and coracoid), which are absent in other mammals.
Single passages differ from placental mammals in the absence of nerve structures in the brain called the corpus callosum. The corpus callosum provides a connection between the left and right hemispheres of the brain. Single passages are the only mammals capable of electroreception (a sensation that allows you to find prey using an electric field created by muscle contractions).
Of all the representatives of the detachment, the platypus has the most sensitive level of electroreceptors. They are in the skin of his beak. Using these electroreceptors, the platypus can detect source direction and signal strength. Platypuses shake their heads from side to side while hunting in the water to scan for the presence of prey. Thus, when searching for food, they do not use their eyesight, smell or hearing, but rely only on electroreception.
The remains of single passages are rather scarce, but it is believed that they separated from other mammals in the early stages of evolution, before the appearance of marsupial and placental mammals. There are several single pass fossils from the Miocene era. Fossils from the era include Teinolophos , Kollikodon and Steropodon .
Platypus (Ornithorhynchus anatinus ) - an unusual looking mammal with a wide beak (resembling a duck's beak), tail (similar to a beaver's tail) and webbed legs. Another oddity of the platypus is that the males are poisonous. A spur on their hind limb provides a mixture of poisons that are unique to the platypus. The platypus is the only surviving representative of its family.
There are four living species of echidnas:
- Barton's passage (Zaglossus bartoni),
- Bruyne's Wayway (Zaglossus bruijni),
- Attenborough Drive (Zaglossus attenboroughi),
- Australian Echidna (Tachyglossus aculeatus ).
Echidna - covered with thorns and coarse hair, solitary animals that feed on ants and termites. Although echidna resemble hedgehogs, porcupines and anteaters, they are not associated with any of these groups of mammals. Echidna have short limbs, strong and clawed legs, which makes them good diggers. They have a small mouth and no teeth. They feed, tearing rotten logs, ant nests and barrows, and then lick ants and insects with their sticky tongue. Echidna is named after the monster of the same name from Greek mythology.
The amazing organisms that lay their eggs and feed their young with milk are single-pass mammals. In our article we will consider the systematics and features of the life of this class of animals.
General characteristics of the class Mammals
Mammals, or Beasts, belong to the most highly organized representatives of the Chordate type. Their characteristic feature is the presence of mammary glands in females, the secret of which they feed their cubs.The external features of their structure include the location of the limbs under the body, the presence of hair and various derivatives of the skin: nails, claws, horns, hooves.
For most mammals, the presence of seven cervical vertebrae, the diaphragm, exclusively atmospheric breathing, a four-chamber heart, and the presence of a cortex in the brain are also characteristic.
Single pass, marsupials, insectivores: the origin of mammals
Mammals are characterized by significant species diversity. The platypus, kangaroo, mole, dolphin, whale, monkey, human are all representatives of this class. All of them descended from ancient reptiles. Proof of this fact is the similarity of their embryonic development, the presence of some representatives of the cloaca and crow's bones, and egg laying.
As a result of evolutionary processes and further divergence, orders of mammals arose: monotremes, marsupials, insectivores. The origin of mammals, as well as their subsequent development, has led to the fact that at present this class occupies a dominant position in the system of the animal world. Its representatives have mastered both ground-air and aquatic habitats.
Single Pass Mammals: Fossil Species
Paleontological findings of single pass are few in number. They belong to the era of the Miocene, Upper and Middle Pleistocene. The oldest fossil of these animals is 123 million years old. Scientists have come to the conclusion that the fossil remains practically do not differ from modern species. Single-pass mammals, representatives of which are endemic, live only in Australia and on the adjacent islands: New Zealand, Guinea, Tasmania.
First Beasts - this is represented by just a few species. Single pass mammals include echidna. Due to the fact that her body is covered with long stiff needles, outwardly this animal resembles a hedgehog. In case of danger, the echidna turns into a ball, thus protecting itself from enemies. The body of the animal has a length of about 80 cm, its front part is elongated and forms a small proboscis. Echidna are nocturnal predators. In the afternoon they rest, and with the onset of dusk they go hunting. Therefore, their vision is poorly developed, which is offset by excellent sense of smell. Echidna have burrowing limbs. With the help of their and sticky tongue, they produce invertebrates in the soil. Females usually lay one egg, which is hatched in the skin fold.
These are also representatives of the class Mammals, the order One-pass. They differ from their closest echidna relatives by a longer elongated proboscis, as well as the presence of three fingers instead of five. Their needles are shorter, most of them are hidden in the wool. But the limbs, on the contrary, are longer. Passages are endemic to the island of New Guinea.
The basis of the diet of these single pass are earthworms and beetles. Like the echidna, they catch them with a sticky long tongue, on which there are numerous small hooks.
Subclass Real Animals
Single pass mammals are primarily characterized by the presence of cloaca. Real animals have separate openings for the digestive, reproductive, and urinary systems. In this subclass, marsupial and placental mammals are isolated.
Representatives of this systematic unit have a leather bag on their belly. Some single pass mammals also have this feature. But at marsupials in it ducts of mammary glands open. Most of these animals live in Australia, but the possum is also found in North America.
The most famous representative of the order Marsupials is a kangaroo. This is a large mammal that moves in leaps. Their length can reach up to 1.5 m. Thanks to the well-developed hind limbs and tail, they move very quickly. Kangaroos can reach speeds of up to 50 km / h. These herbivores are often attacked by various predators.They are protected by the hind limbs, resting on the tail.
A marsupial bear, also called a koala, lives in southern Australia. This cute animal sits motionlessly in the trees all day. And at night he goes to an active lifestyle. The diet of koalas consists of leaves and young shoots of eucalyptus. These animals are quite voracious. They can eat up to a kilogram of food per day. The meat of koalas is inedible, but fur is of great value to humans. For this reason, this species was practically on the verge of extinction. At this time, this animal is listed in the International Red Book.
Marsupials have mastered several habitats. Most of them are terrestrial animals. Some live in trees. This is a koala and a marsupial flying squirrel. Some species live underground. These include the possum.
And marsupials are dioecious animals with internal fertilization. The most progressive structural features are placental representatives of this class. They are most prevalent in nature. During embryonic development, they form a child's place or placenta. This is the organ that provides the connection of the embryo with the mother's body. The placental pregnancy period is from 11 days in mouse rodents to 24 months.
This group of mammals is represented by a large number of orders. So, the representatives of Insectivores are hedgehogs, moles, muskrats, shrews, shrews. Their common feature is not only the nature of the food, but also the appearance. The front section of the head of the carnivore is elongated and forms a short proboscis, on which there are sensitive hairs.
Placental mastered all habitats, except the organism. Bats are capable of flying due to the presence of a skin fold between the fingers, which serves as their wing. The pinnipeds spend most of their lives in the water, and the Cetaceans live there constantly. Terrestrial placental include Rodents, Hares, Pairs - and Equids, Predatory and Primates. The man represents the last squad.
Mammals - monotremes, marsupials and placental feed their young with milk. Each of these superclasses has its own characteristics. In One-pass, cloaca is preserved, in marsupials, a skin fold is formed in which a newborn develops for a certain period. All of them are endemic to Australia. Marsupials and single pass mammals do not have a placenta. Due to the presence of an organ that binds the body of the mother and child during the period of fetal development, completely viable individuals appear. Therefore, placental are the most highly organized representatives of the class.
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The name is due to the fact that the intestine and urogenital sinus enter the cloaca (similarly in amphibians, reptiles and birds), and do not go outside in separate passages.
Detachment One-pass, or Oviparous (Monotremata) (E. V. Rogachev)
Single-pass (or ovipositing) - the most primitive among modern mammals, retaining a number of archaic structural features inherited from reptiles (egg laying, the presence of a well-developed coracoid bone not connected to the scapula, some details of the articulation of the skull bones, etc.). The development of the so-called marsupial bones (small pelvic bones) in them is also considered a legacy of reptiles.
By the presence of distinct coracoid bones, single pass differ from marsupials and other mammals in which this bone has become a simple outgrowth of the scapula. At the same time, the hairline and mammary glands are two interrelated signs characteristic of mammals. However, the oviparous mammary glands are primitive and structurally similar to the sweat glands, while the mammary glands of marsupials and higher mammals are cluster-shaped and look like sebaceous glands.
Quite a number of similarities between monotremes and birds - traits are adaptive rather than genetic. The laying of eggs by these animals brings monotremes closer to reptiles than to birds. However, the yolk in monotremes is much less developed than in birds. The keratinized egg shell consists of keratin and also resembles the shell of a reptile egg. Birds are also reminded of such structural features as a certain reduction of the right ovary, the presence in the digestive tract of pockets resembling bird goiter, and the absence of an external ear. However, these similarities are more adaptive in nature and do not give the right to talk about some kind of kinship directly with one-pass and birds.
In adult ovipositing teeth are missing. In 1888, milk teeth were discovered in a platypus cub, which disappear in an adult animal, these teeth are diverse in structure, like in higher mammals, and the two largest teeth on each jaw have the location and appearance of molars. According to body temperature, single-pass occupy an intermediate position between poikilothermic (reptiles) and true warm-blooded (mammals and birds). The temperature of the echidna fluctuates around 30 °, the platypus - about 25 °. But these are only average figures: they vary depending on the temperature of the environment. So, the temperature of the body is viper when the temperature of the medium changes from + 5 ° to + 30 ° C, it increases by 4-6 °.
Currently, the single-pass squad has 5 living representatives belonging to two families: the platypus and 4 species of echidnas. All of them are common only in Australia, New Guinea and Tasmania (map 1).
Map 1. Spread of Echidnus and the Platypus
Platypus family (Ornithorhynchidae)
The only member of the family is platypus (Ornithorhynchus anatinus) - was discovered at the very end of the XVIII century. into the period of colonization of New South Wales. A platypus was first mentioned in an animal list of this colony in 1802 as “an amphibian animal of the genus of moles. Its most curious quality is that it has a duck beak instead of a regular mouth, which allows it to feed in silt like birds.” It was also noted that this animal digs its hole in its claws. In 1799, Shaw and Nodder gave him a zoological name. European colonists called him "platypus", "duck-duck", "water mole". Currently, Australians call it "platypus".
Fig. 14. Platypus (Ornithorhynchus anatinus)
The very first scientific description of the platypus laid the foundation for fierce debate. It seemed a paradox that a mammal covered with wool could have a duck beak and legs with membranes. The first platypus skins brought to Europe were considered a fake, a product of skillful oriental taxidermists who deceived the gullible European sailors. When this suspicion was dispelled, the question arose of which group of animals to attribute it to. The "secrets" of the platypus continued to be revealed: in 1824, Meckel discovered that the platypus has glands that secrete milk. It was suspected that this beast lays eggs, but it was proved only in 1884.
The platypus is an animal with brown fur, about 65 cm long, including the length of a flattened tail, similar to the tail of a beaver. The head ends with the famous "duck beak", which is actually just a muzzle in the form of an expanded beak, covered with a special kind of skin rich in nerves. This "beak" of the platypus is a tactile organ, which also serves for food.
The head of the platypus is round and smooth, there is no external ear. The forepaws are strongly webbed, but the membrane that serves the animal when swimming folds when the platypus walks on land or if it needs claws to dig burrows. The membranes on the hind legs are much less developed. The forefeet play the main role when digging and swimming, the hind limbs are of great importance when moving on land.
In the water, the platypus usually spends about two hours a day. He feeds twice: early in the morning and in the evening twilight. Most of the time he spends in his hole on land.
The platypus eats small aquatic animals.He stirs with his beak silt at the bottom of the reservoir and catches insects, crustaceans, worms and mollusks. Under water, he feels free, unless, of course, there is an opportunity from time to time to breathe on the surface. Diving and rummaging in silt, he is guided mainly by touch, his ears and eyes are protected by fur. On land, the platypus, in addition to touch, is guided by vision and hearing.
Fig. 15. Various platypus poses
The platypus’s holes are located outside the water, including the entrance located somewhere below the overhanging shore at an altitude of 1.2-3.6 m above water level. Only an exceptionally high flood can flood the entrance to such a hole. An ordinary hole is a semicircular cave dug under the roots of trees, with two or more entrances.
Every year, the platypus falls into a short winter hibernation, after which it begins a breeding season. Males and females are found in water. The male grabs the female’s tail with its beak, and for some time both animals swim in a circle, after which mating occurs.
When the time comes for the female to lay eggs, she pulls out a special hole. First, digs a gallery from 4.5 to 6 in the slope of the shore mat a depth of approximately 40 cm below the surface of the soil. At the end of this gallery, a female tears out a nesting chamber. In water, the female searches for material for the nest, which then, using her tenacious tail, brings it to the hole. She builds a nest from water plants, willow twigs or eucalyptus leaves. Too hard material, the future mother carefully crushes. Then it clogs the entrance to the corridor with one or more earthen plugs, each 15-20 thick cmThe cork is made using a tail that uses a spatula as a bricklayer. Traces of this work can always be seen on the tail of the female platypus, which in its upper part is shabby, hairless. Thus, the female clogs itself in a dark shelter inaccessible to predators. Even a man for a long time could not reveal the secret of her nest shelter. Having finished this painstaking and difficult work, the female lays eggs.
The first time a platypus laid eggs was laid in 1884 by Caldwell in Queensland. After that, she was traced in the Hillsville Nature Reserve in Victoria. These eggs are small (less than 2 cm in diameter), rounded, surrounded by a dirty white shell, consisting not of lime, as in birds, but of a soft, elastic horn-like substance, so that they can easily be deformed. Usually there are two eggs in a nest, sometimes one, three, or even four.
The duration of incubation may vary. The well-known expert on Australian animals, David Fley, found that the incubation in the platypus does not exceed 10 days, and can last only a week, provided that the mother is in the nest. During incubation, the female lies, in a special way, curving, and holds the eggs on her body.
The mammary glands of the platypus, discovered by Meckel in 1824, are nipple-free and open outward with simple expanded pores. Of these, milk flows down the mother’s hair, and the licks lick it. They are growing fast. During their feeding, the mother also eats hard, a case is known when a nursing female ate earthworms and crustaceans overnight in an amount almost equal to her own weight.
The cubs are blind for 11 weeks, then their eyes open, but they continue to remain in the hole for another 6 weeks. These cubs, which feed only on milk, have teeth; as the animal grows, the milk teeth disappear and are replaced by simple horn plates. Only after 4 months the young platypuses go on their first brief excursion into the water, where they begin to clumsyly search for food. The transition from milk to adult is gradual. Platypuses are well tamed and survive in captivity until the age of 10.
Platypuses are found in Queensland, New South Wales, Victoria, some points in South Australia and Tasmania. Currently, they are most numerous in Tasmania (map 1).
The platypus is not very demanding on the composition of the water in which it seeks food.It carries both the cold and clear waters of the mountain streams of the Australian Blue Mountains, and the warm and muddy waters of the rivers and lakes of Queensland.
Quaternary platypus remains found in southern Queensland. Fossil platypuses resembled modern ones, but were smaller in size.
Before the person moved to Australia, the enemies of the platypus were few in number. Occasionally he was attacked only monitor lizard (Varanus varius), python (Pithon variegatus) and a seal swimming in the rivers sea leopard. The rabbits introduced by the colonists created a dangerous situation for him. By digging holes rabbits everywhere bothered the platypus, and in many areas it disappeared, giving way to territory. European settlers also began to pursue the platypus for the sake of his skin. Many animals fell into traps set on the banks of the rivers for rabbits, and in the tops of fishermen.
Wherever people destroyed or bothered the platypus, the surviving animals left these places. Where a man did not bother him, the platypus perfectly endured the neighborhood with him. To ensure the existence of the platypus, the Australians created a system of reserves and "shelters", among which the most famous are the Hillsville Preserve in Victoria and the West Burley Preserve in Queensland.
The platypus is an easily excitable, nervous animal. According to D. Fley, the sound of a voice or steps, some unusual noise or vibration, is enough for the platypus to go out of balance for many days or even weeks. Therefore, for a long time it was not possible to transport platypuses to zoos in other countries. In 1922, the first platypus ever seen in other countries arrived in the New York Zoo, where he lived only 49 days, every day for an hour he was shown to the public. Transportation was made possible thanks to G. Barrell, who invented an artificial housing for the platypus, consisting of a reservoir of water (reservoir), a sloping labyrinth that imitates a hole with a rubber "soil", and a supply of worms to feed the animal. To show the animal to the public, the wire cover of the residential chamber of the platypus burrow was displaced.
In the same zoo in New York, platypuses were imported twice: in 1947 and 1958. These transportations were organized by D. Flea. In 1947, three platypuses were transported to New York by sea, one of them died after 6 months, and the other two lived in the zoo for 10 years. In 1958, three more platypuses were transported to New York by plane.
Echidna Family (Tachyglossidae)
Echidna, covered with needles, like porcupines, but reminiscent of anteaters in type of nutrition, belong to the second family of the one-pass detachment. The sizes of these animals usually do not exceed 40 cm. The body is covered with needles, the length of which can reach 6 cm. The color of the needles varies from white to black. Under the needles, the body is covered with short brown hair. The echidna has a thin, pointed muzzle length of 5 cmending in a narrow mouth. Around the ears, longer tufts of fur are usually developed. The tail is almost not expressed, there is only something like a protrusion at the back, covered with needles (Table 2).
Table 2. Oviparous and marsupials. Australian Echidna (Tachyglossus aculeatus)
Strong limbs of the echidna bear 5 spade-shaped claws each (in the New Guinean prochidina, only 3 claws are developed). The second claw on the hind legs is especially developed, it is curved and serves echidna to scratch the skin: many parasites settle between her needles, like our hedgehog and porcupine. The Tasmanian echidna with shorter and rarer needles does not need a highly developed carding claw, and it is much shorter.
Currently, there are 2 genera of echidnas: actually echidn (genus Tachyglossus) living in Australia, and New Guinea Projects (genus Proechidna). There are 2 species in the genus Tachyglossus: Australian Echidna (T. aculeatus), one of the subspecies of which is endemic to New Guinea, and Tasmanian Echidna (T. se
tosus), characterized by larger sizes and thick wool, from which stick out rare and short needles. The difference in fur coat of these animals is probably related to the colder and wetter climate of Tasmania.
Echidna is found in Australia, in the eastern half of the mainland and on its western tip, in Tasmania and New Guinea. Tasmanian echidna is found in Tasmania and on several islands of the Bass Strait.
The discovery of the echidna at the beginning of the colonization of New South Wales did not immediately receive the attention it deserved. In 1792, Shaw and Nodder described the Australian echidna and named it Echidna aculeata. In the same year, the Tasmanian species was discovered, described by Geoffrey as Echidna setosa. Echidna is a purely terrestrial animal. She lives in a dry bush (bushes), preferring rocky areas. Nor she does not dig. Her main defense is needles. Worried, the echidna curls into a ball like a hedgehog. With the help of claws, it can partially dig into the loose earth, burying the front of the body, it exposes the enemy only needles pointing back. During the day, hiding in the voids under the roots, stones or hollows, the echidna is resting. At night, she goes in search of insects. In cold weather, she stays in her den, falling into non-prolonged hibernation, like our hedgehogs. Stocks of subcutaneous fat allow her, if necessary, to starve for a month or more.
The brain of the echidna is more developed than the platypus. She has a very delicate hearing, but poor eyesight: she sees only the closest objects. During his excursions, mainly overnight, this animal is guided mainly by the sense of smell.
Echidna feeds on ants, termites and other insects, and sometimes other small animals (earthworms, etc.). She ruins anthills, moves stones, pushing them with her paws, even rather heavy ones, under which worms and insects hide.
The strength of the echidna muscles is amazing for a small animal of this size. They talk about a zoologist who locked a viper for the night in his kitchen. The next morning he was very surprised to see that the echidna had moved all the furniture in the kitchen.
Having found an insect, the echidna throws out its thin, long and sticky tongue, to which prey sticks.
The echidna's teeth are absent at all stages of its development, but on the back of her tongue there are horn teeth, which rub against the combed palate and rub the captured insects. With the help of the tongue, the echidna swallows not only insects, but also the earth and particles of rock detritus, which, getting into the stomach, complete the grinding of food, similar to how it happens in the stomach in birds.
Like the platypus, the echidna hatches eggs and feeds the young with milk. A single egg is placed in a primitive bag, which is formed by the breeding season. How the egg enters the bag is still unknown. Mr. Burrell proved that the echidna can not do this with the help of paws, and put forward another hypothesis: she has a flexible body so that, curving, the female could lay the egg directly into the abdominal bag. One way or another, the egg “lays out” in this bag, where the cub hatches from it. To get out of the egg, the cub breaks the shell with a horn cone on its nose.
Fig. 16. The ventral side of the female is echidna. Visible front bag
Then he puts his head in the hair-covered pouch where the mammary glands open, and licks the milk secretions from the hairs of this pouch. The baby is in the bag for quite some time until the needles begin to develop. Then the mother leaves him in some shelter, but for a while she visits him and feeds him with milk.
The echidna tolerates bondage well if she has protection from the excess of the sun, from which she suffers greatly. She enjoys drinking milk, eating eggs and other food that can fit in her narrow, elongated mouth. Her favorite delicacy is raw eggs, in the shell of which a hole has been punched where the echidna can stick its tongue. Some echidna lived in captivity until the age of 27.
Aborigines who love to eat echidna fat often hunted for it, and in Queensland they even specially trained dingoes for hunting echidna.
Passageways (genus Proechidna) are found in New Guinea.They differ from Australian echidnas in a longer and curved muzzle ("beak") and high three-fingered limbs, as well as small outer ears. In the Quaternary, two extinct species of echidnas are known, but this group is not known in older sediments. The origin of the viper is as mysterious as the origin of the platypus.
Fig. 17. Black-Needle Prochidna (Proechidna)