Echidnas, also known as spiny anteaters, are medium-sized mammals with hollow, barbless spines covering their body. Although they resemble hedgehogs (family Erinaceidae) and porcupines (families Hystricidae and Erethizontidae) in appearance, echidnas constitute a separate family, Tachyglossidae. Along with the platypus, they fall under the order Monotremata, which comprises all egg-laying mammals (monotremes).
Currently, there are 4 species of echidnas grouped under two genera: Tachyglossus and Zaglossus. While the first genus is monotypic, with a single species, the short-beaked or short-nosed echidna, the latter has 3 species, namely the Eastern, Western, and Sir David’s long-beaked echidna.
While long-beaked echidnas are endemic to New Guinea, the short-beaked echidna is found in both New Guinea and mainland Australia. They are typically solitary and feed on worms and insects, such as ants and termites, depending on the species.
On average, echidnas range from 14 to 30 in (35.5 to 76.2 cm) in length. The smallest species, the short-beaked echidna, measures between 12 and 18 in (30 to 45 cm) long. In contrast, the three species of long-beaked echidnas are larger, typically reaching around 24 in (60 cm), with one recorded individual measuring an impressive 39 in (100 cm).
Females of short-beaked echidnas weigh around 9.9 lb (4.5 kg), while males are about 33% heavier, averaging 13 lb (6 kg).
Echidnas have medium-sized bodies covered by numerous hollow, barbless spines. These keratinized spines are beige-and-black in color and measure about 2 in (5 cm). A layer of black or brown fur also covers the body of these animals.
They have small faces with elongated, slender snouts, often referred to as beaks, which serve as both their mouths and noses. Their eyes are small and beady, their jaws are toothless, and their ears appear as simple slits on the sides of their heads.
Like the platypus, echidnas have numerous sensory electroreceptors on their snout. The short-beaked echidna bears about 400 receptors, while the large-beaked echidnas have as many as 2,000 of them on the tip. These receptors help echidnas sense electric fields generated by prey in their surroundings.
These animals have short yet strong limbs that are well-adapted for digging through soil. Their hindlimbs are equipped with long claws that curve backward, and in males, the ankles bear non-venomous tarsal spurs, the role of which is still under study.
Male echidnas possess a characteristic four-headed penis, which remains retracted inside a preputial sac (found in the cloaca) when not in use, and protrudes out of the cloacal opening during mating. The penis is about 7 cm (2.8 in) long when erect and contains penile spines that are believed to help induce ovulation in females.
Females have a two-branched reproductive tract with two functional ovaries, oviducts, and uteri. Both sexes, however, have a single cloaca that serves as the common opening for excretion and mating.
These animals derive their name from Echidna, a Greek mythological monster who was partly woman and partly snake[1]. Such etymology seems fitting for echidnas, as these animals possess qualities of both mammals and reptiles.
The four species of echidnas are grouped under two extant genera: Tachyglossus and Zaglossus.
The three species of long-beaked echidnas are native to New Guinea, whereas the short-beaked echidna is spread across the southern, southeastern, and northeastern regions of New Guinea as well as in mainland Australia.
Echidnas are typically found in woodlands and forests, where they hide under vegetation, rock crevices, or debris to avoid harsh climates. The short-beaked echidna, in particular, also takes shelter in burrows built by other animals, such as rabbits and wombats.
While the long-beaked echidnas are typically found living in leaf litter on the forest floor of cool, wet montane forests, their short-beaked counterparts are found in almost all habitats in Australia, ranging from the snow-covered Australian Alps to the deserts of the Outback. The latter prefer living in areas with abundant termite and ant colonies.
The short-beaked echidna typically feeds on ants and termites. Long-beaked echidnas, on the other hand, specialize in earthworms, only occasionally consuming other invertebrates, especially insect larvae and, to a lesser extent, ants.
Like all young mammals, echidnas initially feed on their mother’s milk.
Echidnas are primarily solitary and maintain large, mutually overlapping territories. They congregate only during the breeding season.
These animals are active both during the day (diurnal) and at evening (crepuscular), depending on the ambient temperature and season, as well as the availability of resources. Though terrestrial, they are excellent swimmers and often visit water bodies for bathing.
Echidnas use the sensitive electrosensors in their snouts to locate their prey. Using their claws, they break open anthills and soft logs, then slurp up insects or worms with their long, sticky tongues. Since they lack teeth, they use their tongues to press the food against keratinized ridges in the bottom of their mouths.
Apart from fleeing from danger, echidnas may engage in other defensive strategies to save themselves. Like hedgehogs, they can curl up, either completely or partially, tucking in their faces and feet while exposing their spines to deter predators. Additionally, they use the curved claws on their hind limbs to dig into the soil and anchor themselves firmly, so that the predators cannot snatch them away easily.
The short-beaked echidna has an average lifespan of about 10 years in the wild, whereas in captivity it can survive over 40 years under proper care[4].
While little is known about the lifespan of long-beaked echidnas in the wild, they are estimated to survive between 10 and 16 years. In captivity, they can live between 30 and 40 years.
The breeding season of echidnas typically begins in late June and extends through September. During this period, males form a queue or train of up to 10 individuals standing nose to tail, with the youngest male typically at the end[5]. The train continues to follow the female till she is ready to mate.
Once receptive, the female lies flat on her stomach while the pursuing males dig a circular trench around her. The largest male outcompetes all rival males and lies where the female rests, aligning his cloaca with hers to mate.
After a gestation period of about 22 days, the female lays a single soft-shelled, leathery egg that is about 0.55 in (1.4 cm) long and weighs around 0.05 to 0.07 oz (1.5 to 2 gm). The egg is deposited directly into a temporary pouch in which the young is carried till it is ready to hatch.
About 10 days later, the fetus-like young echidna (also called a puggle) hatches by using its pointed egg tooth and a fleshy bulb called the caruncle to break through the leathery shell. The puggle latches onto the pores of the milk patches on the mother’s body and suckles on them. It remains in the pouch for about 45 to 55 days, during which it slowly starts to develop the spines.
After some time, the mother digs a nursery burrow and transfers the young to it, returning every few days (typically every 5 days) to feed the young. At around 7 months, the puggle is weaned, though it continues to stay within its mother’s den for up to a year, after which it slowly ventures into the outside world independently.
Their predators include foxes, goannas, feral cats, and domestic dogs. Young echidnas are particularly susceptible to attacks by snakes, which slither into their burrows.
Of the four species, only the short-beaked echidna belongs to the Least Concern (LC) category of the IUCN Red List of Threatened Species. The other three are listed under the following categories.
| Species | IUCN Category |
|---|---|
| Sir David’s Long-Beaked Echidna & Western Long-Beaked Echidna | Critically Endangered (CR) |
| Eastern Long-Beaked Echidna | Vulnerable (VU) |
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