Echidna
| Echidna | ||||||||||||
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Short-billed hedgehog ( Tachyglossus aculeatus ) |
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| Tachyglossidae | ||||||||||||
| Gill , 1872 | ||||||||||||
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The echidna (Tachyglossidae), also called echidnas or echidna called, are a family of egg-laying mammals . They form with the platypus , the order of monotremes (monotremes). Along with these, they are the only remaining mammals that do not give birth to their offspring alive . The family is divided into two genera with a total of four species, the short-billed urchin ( Tachyglossus aculeatus ) and the three types of long- billed urchin ( Zaglossus ).
distribution
Echidna are found in Australia , Tasmania and New Guinea . The short-billed hedgehog is distributed over large parts of Australia including its offshore islands and New Guinea. The long-billed hedgehogs, on the other hand, are endemic to New Guinea .
description
Build and coat
With the compact body and the spines on the back and on the side, the Echidna resemble the hedgehog , with which they are not closely related. They have only developed convergent to those . The spines are hollow and up to 6 inches long. They are usually yellowish in color, whereby the tip can be black. The rest of the fur is brownish or black in color. Sometimes the hair is so long that the spines are hidden underneath. The length of the hair depends on the climate in the respective habitat of the animals. They are longer and denser in a colder environment than in a warmer environment. In the long-billed hedgehog, the spines are generally shorter, more blunt and sparsely distributed.
With a head body length of 35 to 53 centimeters and a weight of 2.5 to 7 kilograms, the short-billed urchin is the smaller species, while the long-billed urchin can reach a head body length of 45 to 77 centimeters and a weight of up to 16 kilograms. Males are usually slightly larger and heavier than females. The short, stubby tail is covered with spines on the top and bare on the underside. As with all monotones, the excretory and sexual organs flow into a common opening, the cloaca .
The body temperature averages 31 to 33 ° C, comparable to that of platypus, and is therefore significantly lower than that of most other mammal species. Echidna also cannot regulate their body temperature to the same extent as other mammals. Another special feature compared to most mammals is the chromosomal gender differentiation, which regularly follows the scheme 64, X 1 X 1 X 2 X 2 X 3 X 3 X 4 X 4 X 5 X 5 for females, but 63, X 1 Y 1 X 2 Y 2 X 3 Y 3 X 4 Y 4 X 5 for males follows.
limbs
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Echidna have short, stocky limbs. These each end in five toes, of which - depending on the species - either all five (in the short-billed urchin) or only the middle three (in the long-billed urchin) have grave claws. The second toe of the hind feet is extended and is used for grooming. Similar to the platypus , most male ant urchins have a sting on the ankle of their hind legs. While all newborn animals still have this sting, most females, but also some males, lose it in the course of their development. However, unlike the platypus, this sting does not contain poison. During the mating season, the males' stings secrete a secretion whose function is not yet known.
Head and sense organs
The Echidna's small head sits on a very short neck and ends in a long, tubular snout. In the case of the long-billed hedgehog this is longer and curved downwards, in the case of the short-billed urchin it is straight. The mouth opening is very small, just big enough to stick out the sticky tongue , which is up to 18 centimeters long . Echidna have no teeth; instead, they have horn plates on the back of the tongue and roof of the mouth that are used to chop up food. Your sense of smell is well developed. The nostrils are placed at the tip of the muzzle just above the mouth. One thing they have in common with platypus is a special perception system in the snout. Sensitive electroreceptors react to the weak signals that the muscle movements of their prey produce and serve to locate and catch the prey. Long-billed ant urchins have small ears, whereas short-billed ant urchins do not. The eyes are small and sit relatively far in front of the head.
Way of life
Much of the information below is only known from the short-billed urchin, which has been researched far better than the long-billed urchin of New Guinea. It is believed, however, that their way of life is in most cases the same as that of their Australian relatives.
habitat
Echidna make no special demands on their habitat. They can be found anywhere there is enough food for them. They live in the desert regions in the interior of Australia as well as in forest areas and parklands. In the mountainous regions of New Guinea they can be found up to 4000 meters above sea level as well as at sea level. Echidna do not necessarily need trees in their habitat; Hollow tree trunks as well as crevices in the rock or small burrows can serve as resting places.
Locomotion
Echidna are ground dwellers. Your locomotion is usually characterized by a slow, dragging pace. The feet are stretched out when walking so that the stomach is relatively far from the ground. The toes of the hind legs are turned outwards. With their gait, they get along well in rugged, rocky terrain. In addition, they can swim very well.
Activity times and social behavior
The activity times of the Echidna depend to a certain extent on the habitat and the season. They are usually crepuscular animals that mainly forage in the early morning and early evening. In hot regions and in summer, their activity shifts more towards night, in cooler areas and in winter more towards day. Due to the lack of ability to regulate body temperature, they are only active up to a maximum of 32 ° C outside temperature. At very cool temperatures they fall into a torpor , a cold rigor. The occurrence of the torpor depends less on the outside temperature than on the available food. If there are enough prey animals, this will not occur. In the mountains of southern Australia, ant urchins fall into a hibernation-like state in which their body temperature drops to just under 4 ° C. You lose two to three percent of your weight per month.
Echidna live solitary outside of the mating season, are true to location, but have no territorial behavior. They inhabit areas that are between 25 and 200 hectares in size and often overlap.
nutrition
The Echidna are carnivores , whereby the size of their prey is limited by the small mouth opening. Short-billed hedgehogs primarily eat ants and termites , while the long-billed hedgehog's diet consists mainly of earthworms .
With their snouts they break up rotten wood, rummage through fallen leaves and other plant material on the ground or poke into crevices in the rock. The above -mentioned electric receptors serve to locate the prey, and their exact function is not yet known. Sometimes they break open termite burrows with their claws to get at prey. With their long sticky tongues, the prey is carried into the mouth and then chewed.
Predators and defense behavior
If they feel threatened, they dig themselves into the ground very quickly. They then wedge themselves with the strong limbs and only let the prickly top protrude from the ground. In the event that the ground is too hard, like the hedgehog , they can curl up into a prickly ball. This defensive tactic works so well that Echidna have few natural enemies. Young animals sometimes fall prey to colored monitor lizards , whereas adult animals are sometimes hunted by introduced species such as the dingo or the red fox .
Reproduction
Mating behavior
The mating season is usually in July and August. During this time there is a strange behavior: the otherwise solitary animals form caravans, the front animal being a female, followed by up to ten males. In this way, the males go after the female and poke her snout over and over again. Pheromones sent by the female are a signal to the male that he is fertile. Sometimes it also happens that males pursue a female who is not ready to mate. In this case, it ignores the males or, in the case of persistent pursuer, even curls up into a ball of spikes, so that the males ultimately have to find another partner to run after. This persecution can drag on for days, sometimes weeks. It is very exhausting for the males, who can lose up to 25% of their body weight.
When the female is ready to mate, she lies flat on her stomach, her head often hidden in the bushes. The males begin to dig behind the female or to the left and right of her. If many males are involved, this “mating ditch” can form a real ring around the female. Then the males begin to push each other out of the ditch with their heads until only one remains. This then lies laterally behind the female in the mating ditch. It now strokes the female's spines and fur and tries to lift its tail with its hind legs. This foreplay can last up to four hours. If the female can finally be picked up, the male inserts his penis into the cloaca. The sexual act can last up to 180 minutes. Immediately afterwards, both animals go their separate ways again. While the female mates only once a season, the male sometimes joins a caravan behind another female.
Egg laying and rearing of young
Around three to four weeks after mating, the female usually lays one egg , rarely two or three. There are different reports on the long-billed hedgehog, while some sources usually speak of one egg, others report four to six. Echidna eggs are about the size of a grape and cream-colored, they have a leathery shell and a large yolk. Before laying the egg, the female forms a pouch on her stomach. Immediately after laying, the egg is transported into the belly pocket, where it is incubated for ten days. The hatchling breaks through the shell with the help of an egg tooth . Young animals are around 15 millimeters long when they hatch, naked and blind and resemble newborn marsupials in their embryo-like state . In the bag there are mammary glands that the young animal sucks or licks on, because the mother animal has no teats, but a milk field from which the milk comes out as soon as the young licks. It stays in the bag for around eight weeks, after which its spines grow and it has to leave it. At this point it is around 6 to 8 inches tall. The mother puts it in a well-hidden burrow, e.g. B. under a root, and only returns every five to ten days to suckle it. After ten weeks the eyes open, after five to six months the young animal makes its first excursions out of the burrow. It is weaned at seven months and leaves its mother at around a year old. Sexual maturity occurs at around one to two years. The mother is ready to mate again two years after the birth.
Life expectancy
Echidna are relatively long-lived animals; wild specimens can live to be over 20 years. The highest known age of an animal in human care was over 50 years.
Systematics and history of development
Echidna and their relatives, the platypus are the mammals associated because mammals do not have their Gebärweise but about their common ancestry be defined. All mammals also have some characteristics in common, which the Echidna also have. These include, for example, the three ossicles (hammer, anvil and stirrup), the presence of hair and suckling the offspring with milk . Although the earliest mammals were likely to lay eggs , the monotremes are not the ancestors of the pouches or placentas , but rather represent a side branch that has specialized in further development and has retained the original characteristic of laying eggs.
Knowledge of the fossil history of the ancestors of the Echidna Echinacea is very poor. The oldest known fossil finds come from the Pliocene era from Australia and are already similar in physique to the more recent species. However, the evolution of animals is undoubtedly older. It is believed that they developed in the Cretaceous Period . Skull remains of the species Zaglossus ramsayi , which is sometimes classified in the genus Megalibgwilia , come from the Pliocene in New South Wales . The length of the animal is estimated to be around 75 centimeters. Zaglossus hacketti was the largest ant urchin found to date. It was about one meter long and 30 kilograms in weight and lived in the Pleistocene in Western Australia until about 15,000 years ago. Outside of Australia and New Guinea, there is no evidence of Echidna Echinacea.
The Echidna family is divided into two genera: the short-billed urchin ( Tachyglossus ) and the long- billed urchin ( Zaglossus ). In the past, both genera were divided into several species, later these were combined as subspecies of one species each. There are now three types of long-billed hedgehog , including the species Z. attenboroughi , which was newly discovered in the mountains of New Guinea in 1998 , which means that four species of anthers are known today. However, some researchers assume that there are even more species - see the respective generic articles for more information.
Echidna and humans
Aboriginal and Papuan
The natives of Australia and New Guinea hunted the Echidna for their meat, with the long-billed hedgehog in particular being considered a delicacy in New Guinea. In some regions of Australia, the Aborigines used the spikes as an ornament, for example on spears. Several stories from the Aboriginal dream time tell how the animal got its spines. In one story, it was thrown into a thorn bush by the other animals as a punishment for hiding a waterhole during the dry season. The thorns stayed in his back and provided the animal with the spiked clothing.
After the arrival of the Europeans
William Bligh , the well-known captain of the Bounty and later governor of New South Wales , made a meticulous drawing of an animal around 1790 before he ate it. This is considered to be the earliest European representation of an ant urchin. The first detailed description of the short-billed hedgehog appeared in Great Britain in 1792 . The first scientific description of the short-billed hedgehog (as well as that of the platypus) comes from George Shaw , its proposed name Myrmecophaga aculeata is an indication that he still assigned the animal to the anteater (Myrmecophagidae). Echidna , the English name of the animals, goes back to the Greek legendary figure Echidna , who was half human and half snake. Like the legendary figure, the ant urchin, with the familiar shape of the hedgehog from Europe and its strange snout, gives the impression of a composite being. It was not until the end of the 19th century that the unusual way of reproducing these animals was discovered. Many details about mating behavior weren't discovered until the 1980s and 1990s.
As the national symbol of Australia, the ant urchin plays a subordinate role in contrast to kangaroos or the koala . However, Millie, the Echidna , was one of the three mascots at the 2000 Summer Olympics in Sydney .
threat
In Australia, the short-billed hedgehog is one of the most widespread native mammals today. The reasons for this are, on the one hand, their lack of demands on the habitat, the abundant food and the property of being able to fall into a torpor when there is a lack of food . Other reasons include good defensive tactics against predators and the fact that they have never been commercially hunted or pursued by Europeans. Similar to the hedgehogs in Europe, a considerable number of them fall victim to road traffic, but they are frequent and not threatened.
More worrying is the species situation in New Guinea. Their habitat is increasingly restricted by clearing forests. In addition, the meat of the long-billed hedgehog is considered a delicacy. Specially trained dogs hunt the animals and bring them down. The International Union for Conservation of Nature lists the long-billed hedgehog as endangered .
literature
- ML Augee: Echidnas of Australia and New Guinea . University of New South Wales (UNSW) Press, Kensington 1997, ISBN 0-86840-046-7 .
- Bernhard Grzimek : Grzimeks animal life . Vol. 10. Mammals 1. Bechtermünz, Augsburg 2000, ISBN 3-8289-1603-1 .
- John A. Long et al. a .: Prehistoric Mammals of Australia and New Guinea . Johns Hopkins University Press, Baltimore 2003, ISBN 0-8018-7223-5 .
- Ronald M. Nowak: Walker's Mammals of the World . 6th edition. Johns Hopkins University Press, Baltimore 1999, ISBN 0-8018-5789-9 (English).
- Peggy Rismiller: The Echidna. Australia's Enigma . Hugh Lauter Levin Associates, 1999, ISBN 0-88363-788-X .
- Ingmar Werneburg, Marcelo R. Sánchez-Villagra: The early development of the echidna, Tachyglossus aculeatus (Mammalia: Monotremata) and patterns of mammalian development. In: Acta Zoologica . 82 (1), 2011, pp. 75-88, doi : 10.1111 / j.1463-6395.2009.00447.x
Web links
- Picture gallery 1 - also of the pairing
- Tree of Life web project Tychyglossidae with further references
Individual evidence
- ↑ Urania Tierreich, Frankfurt / Zurich 1969, Säugetiere, p. 22
