if one speaks of marsupials, one almost always thinks of Australian types of animal and often overlooks on that occasion that marsupials occur also in America. Only there, the bag-rats (Didelphidae) live, the probably most successful marsupial-group at all. In the English usage, all bag-rats are called opossum. However, only the animals, who belong to the type Didelphis, become scientific as opossum marks.
Physique Many of them are external similar mice or rats. The stretched body is 7-45 cm long and runs out into a tail, that often is superior to it in length considerably. The head is long-stretched and pointed. Far outside enough Tasthaare at the muzzle help the animals to certainly move also in the darkness. The ears are small until moderate-sized and only very sparsely hairy. The fur usually is dense, fleecy, colored short and quite differently. The long tail reminds of that of a rat with its flaky skin and the few short hair. However, it can have coated almost completely with fur also with some types. Only its top and a part of the underside remain bare. So, it can do the bag-rats valuable turns as gripping-organ. However, they never gain the skill of a clamp-monkey with it. Some forms position fat-storages in the tail-root and can outlast times with it with bad food-offer.
Hands and feet carry 5 long toes each, that are of each other separate. Thumbs and big-toe, that don't have any claws as single, let themselves compare the other fingers and toes. This way equipped with 4 "gripping-hands" and additionally a gripping-tail, they are sent climbers.
5-27 teats can have distributed over stomach and breast. With inferior number, they often are ordered annular at the stomach. A bag is big and completely trained with some types, with others, it exists only from 2 stomach-continuous, parallel longitudinal-pleats, or it is missing completely. Sundries other characteristics however nevertheless mark it as real marsupials.
The hearing of the bag-rats is enormously fine. its hearing-fortune is enough far in the ultrasound-area in. they can still perceive lutes, that remain the human ear hidden, through it.
Bag-rats are a very original animal-group. they stand if one looks at the family tree of the marsupials, quite far below at the root of this group. Different characteristics like the denture speak with many sharp, sharpened teeth in behalf of it or this 5 each well developed and to grasping suitable fingers and toes all 4 extremity. Bag-rats are quite uniformly built, and exactly therefore, because not it at one completely exactly established environment or food tied is, they could them at the farthest spread marsupial-family becomes.
Nutrition With the food-search, bag-rats are not choosy. The smaller types eat insects mainly. Bigger forms live from birds, small mammals, but also fruits and carrion. If the opportunity emerges, they plunder also nests and consume eggs and boy. Some of them are intrepid robbers, that attack animals and overpower, who are not much smaller than it, themselves. Bag-rats are real omnivores. they can live from worms, snails or reptiles as well like from fruit or carrion. In cities, one could observe how they examined the garbages of the households after food.
Habitat These South American Beutler live above all in the Bodenbewuchs and in the trees of forests and parklands, occurs also in the steppes and semi-deserts, however. In the mountains, one finds it as far as in heights of 4000 m. Even, one can discover it in parks and on street-trees of cities occasionally. Some bag-rats are Kulturfolger. they adapted yourself in its way of life of the surroundings of the human being and could conquer this way new habitats. Also the human being contributed to the expansion of its spread-area, as it some types on West Indian islands, on Madagascar and New Zealand stopped.
Exactly its originality and low adaptation to special conditions are a crucial advantage for the bag-rats. Above all many of the Australian Beutler are on narrow tried at certain habitats or food-conditions. The change of its environment through the human being often led to most outer threat or to the extermination with them. The bag-rats against it don't make any particular demands and can get well ready for new realities.
Silence-ability Another quality helps them, times of unfavorable environment-conditions, as cold or food-lack to survive. they fall into a silence-condition, that corresponds to the hibernation of other animals. The body-temperature sinks, the number of the breaths and heart attacks decreases. The consumption becomes more inferior through it at nutrients. they can live off the fat-reserves, that they positioned in good times under the skin or in the tail-root, until the circumstances are again better. How well this survival-help works, one recognizes that bag-rats reach again and again in the refrigerators of banana-steamers to Europe. they outlast the weeks-long trip between unripe bananas with temperatures of few degree without damage. Even young survive such trips well. This resistance is remarkable particularly with such types, whose tiny boy is not secure in a protective bag, but hangs down freely at the teats of the mother's stomach.
Way of life Bag-rats usually are loners. they oversleep the day in a sure hiding place and emerge only in the evening or at night. The number of its enemies is big. Martens, foxes, lynxes and snakes follow them in its natural habitat, cats and dogs pursue it in populated areas, and also the human being doesn't spare it. its fur is used by garments to feeding and occupying, and because they should be very little sensitive, one uses it as experimental animals many times in laboratories. If they succumb to also the human being, because they are to be simply caught in downfalls, easily, so they are not quite defenselessly delivered its animal enemies. Driven into the narrowness, they turn around in a flash and hold the aggressor its far torn one loudly hissing, before pointed teeth of staring pharynxes contrary to. The jaws can be opened for over 90° on that occasion far. This unexpected threat of the fleeing loot-animal frequently deters the persecutor. Already gives birth, not even small-finger-long bag-rats show this Drohverhalten.
Reproduction Bag-rats are very fertile in the comparison to other marsupials. The boys were born by only 12-13 days after an extraordinarily short Tragzeit. The throw-size can sometimes exceed considerably the number of the teats. All young, whom with it doesn't succeed, to reach a teat perish. The number of the reared boys lies between 4 and 11 in general. they are suckled approximately for 70 days, remains also after it with the mother even longer time, however. they hold on to its back-fur and one can around-carry from her or in the nest look after. Even half-adult bag-rats still often flee with danger on the mother's back. With 6-8 months, they usually already are sexually mature. Is worried for big descendants through this short generation-consequence and the often considerable boy-number. With animals, who have so many enemies, that is a necessary condition to the survived of the type. Bag-rats gain an age of 5-8 years.
System The bag-rats are widespread far over America with 12 types and 76 types. In the north, its habitat is enough as far as into the southern Canada, in the south until approximately 52° more southern breadths to Argentina. However, they are given a home main in South America. Here, they asserted themselves well against all the competition until today.
The wool-bag-rats (type Caluromys) live in Central America and South America as far as after Argentina. its head-torso-length is between 18-29 cm. The soft, fleecy fur is oberseits usually monochrome gray, red or brown and unterseits sallow. The ears and a part of this more than body-long gripping-tail are bare. Instead of a bag, the 7 teats are surrounded only from 2 lateral skin folds. The active animals are on good tried on trees at the climbing way of life. they live from fruits, seeds and soft plant-sharing, however, also insects, reptiles, birds and small mammals eat.
Like shrews, the shrew-bag-rats (type Monodelphis) look. The bare tail is not suitable so good for grasping like with the wool-bag-rats. Sometimes, however, they carry material to the nest-construction in the rolled up tail. they are nightly living ground-inhabitants, can climb quite well, however, however. its food is very diverse. they eat small rodents, insects, fruits, seeds and carrion. Without the protection of a bag, the 8-14 boys are attached to the teats and claw firmly in the mother's peritoneum. If they become older, they ride on its back.
Little, one knows about the 3 types of the short-tail-bag-rats (type Minuania), that live in means and East-Brazil until west-Argentina.
The Chiloë-Beutelratte (Dromiciops australis) lives above all in the dense, moist forests of means-Chile and on the island Chiloë as climbing tree-inhabitants. The animals are mouse-similar, approximately 12 cm long and reached one, densely hairy tail. Only the underside of its top is bare. Females have 4 teats in a small bag. The dense fur of the body is short and silken.
Chiloë-Beutelratten are distinctive night-animals. From branches and leaves, they build small, round nests, that they pad with grass and moss. they live in cooler, restrained areas and hibernate in the cold season, if the feed becomes scarce. They live off the fat, that it stored in the thickened tail-root, on that occasion. they live from insects, snails, worms and other invertebrate small animals.
The bush-tail-bag-rats (Glironia) form a completely unexplored type. One only knows that they live in the moist tropical forests of North-Peru and South-Ecuador.
Also from the Pat-agony-bag-rats (type Lestodelphys), one found only few animals until now. they come from South-Argentina and southeast-Pat-agonies. They advanced with it as all other marsupials farther southward. The big, pointed cuspids are showy at them. they let suspected that these animals are predatorily alive and are adjusted much more strongly than other bag-rats at meat-food.
The dwarf-bag-rats or mouse-opossums (type Marmosa) come along over 40 types of the middle Mexico until North-Pat-agonies before. The excellent climbers are tree-inhabitants, lives also in the Argentinian pampas and in the mountains until 3700 m of height, however. Contrary to its name, dwarf-bag-rats are not always very small. Some types gain the height of a rat approximately with 19 cm of length. The well trained gripping-tail can tower above the body about the double. it is hairless and dense busy with sheds. With almost all types, the big eyes of dark fights are surrounded. The fur is shortly and satin fine. Since dwarf-bag-rats don't have any bag, the boys become hanging dragged along at the mother's teats. Dwarf-bag-rats are night-animals, that live individually and hunt. they eat insects and fruits mainly, but also small rodents, lizards and bird-eggs.
The four-eye-bag-rat (Philander opossum) is widespread. One finds it from the middle Mexico to southeast-Brazil and North-Argentina. The animals look rat-similarly, is considerably bigger with 25-35 cm of length, however. Two shining-white, triangular ones take off stains, that gave its name to the animals, on the dark forehead over the big eyes. The long tail is hairy at the root, the remaining part is bare. The well developed bag is opened to the front and contains 7 teats. Four-eye-bag-rats are excellent climbers, also move skillfully at the ground, however, and are good swimmers. With danger, they rip open hissing its mouth loudly far and know also its sharp teeth to start successfully. they are distinctive night-animals, who become lively only with darkness. Omnivores are lively-ace.
The bare-tail-bag-rat (Metachirus nudicaudatus) is quite similar for the four-eye-bag-rat, has only 2 lateral skin folds instead of a bag, however. One knows very little about its way of life.
The Dick-tail-bag-rat (Lutreolina crassicaudata) occurs all over almost South America in the most different habitats east from the Andes. Although it has a special preference for the proximity of the water, it is no good swimmer, and also its dense, soft fur is not water-repellent. In the branches of the trees, it induces herself just as skillfully as on the ground. it oversleeps the day in tree-caves, round reed-nests or Erdhöhlen. At night, it hunts small mammals, birds, reptiles, fish or insects. Also these animals lack a bag.
Probably the most known bag-rats are the opossums (type Didelphi]). they gave the name to the whole family in the English language-area.
The Schwimmbeutler or Yapok (Chironectes minimus) are one of the most remarkable bag-rats. its spread-area extends from southwest-Mexico to South-Brazil and North-Argentina. There, it digs its residential-caves in the embankments of the waters for himself. it more than body-long tail is hairy only at the root, otherwise it is bare like with a rat. The fur is relatively shortly and fleecy dense. The ear-mussels can be folded and according to the ear waterproof locks. Thickened fingertips with weakly developed claws reminds at the hands of a foliage-frog. Well-developed swimming-skins connect the extended toes together.
A series of characteristics gives a special-position to the Schwimmbeutler among the bag-rats. While most adapted themselves as little as possible in order to be able to live everywhere, the Yapok conquered the water as main habitat. its adaptation goes even so far that the to the back opened bag is waterproof lockable through an especially strong sphincter. A mother with boys in the bag can therefore go on food-search without endangering it. It is uncommon that a bag is trained also with male Schwimmbeutlern. However, it is more weakly than with female animals developed. Yapoks live from cancers, mussels and other small water-animals. To catch fish, only probably rarely succeeds them, because they are relatively slow swimmers. its way of life is very little explored until now, because Yapoks are night-animals and live in badly accessible areas.
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