Echidnas

There are two species of echidna, the short- and long-beaked. The long-beaked is found exclusively in Papua New Guinea and will not be covered here. The short-beaked is found exclusively in Australia and is the subject of this information. All further mention of echidnas refers to this species.

Name
The name echidna derives from the Greek ekhis meaning 'she-viper' and refers to the mythological "mother of all monsters". The scientific name tachyglossus aculeatus, tachyglossus meaning 'fast-tongued'. They are also referred to as spiny-anteaters.

Echidnas are monotremes (along with platypuses, the only species in this order of mammals). Monotremes are egg laying mammals, and this fact, along with several other characteristics has lead many researchers to believe that they are more closely related to reptiles. They 'split' from other mammals at least 120 million years ago.

Distribution
Echidnas are found throughout mainland Australia, as well as Tasmania, King, Flinders and Kangaroo Islands. They are Australia's most widespread native mammal, being found in almost all habitats, from snow covered mountains to deserts. They are common in urban areas, although their camouflage can make them surprisingly difficult to see.

Description
The echidna is "a robust ground-dweller with strong sharp spines covering top of head, back and tail; snout tubular and naked with tiny mouth and nostrils at tip; bulbous forehead."[1] Average length - head and body - is 200-400mm, weight 2.5-7kg, life span to 40 years or more.

The long beak is used for foraging through leaf litter and for breaking into dead wood, searching for food. It is approximately half the length of the head and contains both the nostrils and the mouth. The mouth is toothless, with prey either being crushed with the tip of the beak before being licked up with the long, extendable and sticky tongue, or being crushed between the tongue and the roof of the mouth. It has an excellent sense of smell.

The spines are hollow and thin walled and are typically straw-coloured with black tips. They are in fact modified hairs and are surrounded by fur. This fur keeps the echidna warm and in the colder Tasmania it is so long and dense as to almost conceal the spines.

The legs are short and the feet are adapted for rapid digging, with long and powerful claws. The claws on the hind feet curve backwards to allow for grooming between the spines. The digging ability of echidnas allows them to escape from potential predators by digging straight down, so that only a few spines are still visible above ground. The feet are splayed outwards like a reptile and this gives the echidna its familiar rolling gate.

Echidnas have a lower body temperature than all mammals except the platypus (33 degrees) and this can be varied by 6-8 degrees. They can also enter a state of hibernation or torpor relatively easily and will use this energy saving mechanism at any time of the year

Diet
The lack of teeth preclude the consumption of vertebrates and so the echidna feeds on ants, termites and larvae.

Reproduction
Mating takes place in June to September and is preceded by a period where males will come together in a 'train', following a female (this is the only time that adult echidnas come together). These trains can last for up to 6 weeks before the female is ready to be mated. The train can contain up to 11 echidnas, but 3 or 4 is more common. When ready, the female will stop moving and the males will jostle for position, those not successful leaving the group. The males will dig around the female in order to position themselves slightly below the female.

Peggy Rismillers' studies on Kangaroo Island have found that females only breed every 3-7 years and not until they're about 5-7 years old [2].

Twenty-two days after mating a single, leathery egg will be produced and will be transferred to the pouch. ten days later it will hatch. The young 'puggle' is no more than 1.5cm long and must ravel 6 times its own body length to reach its mothers' milk. Monotremes to not have nipples, instead milk is secreted through the skin patches for the young to suckle on. After seven weeks the puggle has developed so rapidly that it has outgrown the pouch (spines have begun to develop) and hereafter it is left in a nursery burrow, the mother only returning every few days to suckle. After seven months weaning is complete and the mother will abandon her offspring.

Conservation
Echidnas protect themselves by digging themselves into the ground if it is soft, and by curling into a ball if it is not. Cats and monitor lizards are thought to be the main predators of echidna young but dogs will also take adults. Little is known about the numbers of echidnas so it is not possible to have any certainty about the conservation status of these animals. However, their widespread distribution and adaptability means that their future is regarded as secure.

Bibliography
1. Menkhorst and Knight, A field guide to the mammals of Australia, 2001.
2. http://www.abc.net.au/science/scribblygum/June2000/default.htm

Other sources
http://animaldiversity.ummz.umich.edu/site/accounts/information/Tachyglossus_aculeatus.html
http://www.dpiw.tas.gov.au/inter.nsf/WebPages/BHAN-5357K5?open

 

 

 

 

 

 

 

 

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