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The Echidna Is One of the World's Strangest Mammals

The short-beaked echidna (Tachyglossus aculeatus) is one of four living species of echidna. Dave WATTS/Gamma-Rapho/Getty Images

While the echidna (pronounced ih-KID-na) is considered a mammal — because it's warm-blooded, has hair on its body and produces milk for its young — this large hedgehog-like creature is in a class of its own. In fact, the echidna is so different from any other mammal, it puzzles researchers and scientists to this day, according to Rick Schwartz, San Diego Zoo Global Ambassador.

"What really sets the echidna apart from other mammals is it is one of only two egg-laying mammals; the other is the duckbill platypus," says Schwartz in an email interview. "Echidnas are an egg-laying mammal called monotremes. There are only five monotremes in the world: four echidna species, and one platypus species."

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The echidna also has its own distinct look. "Echidnas are monotremes, while hedgehogs are erinaceids and porcupines are rodents," adds Schwartz. "While the echidna is sometimes called the spiny anteater, they aren't even closely related to anteaters."

So, what exactly do these animals look like? To begin, they have a tiny face, with small eyes, and long or short noses (sometimes called beaks). Their body is quite stocky, measuring from 14 to 30 inches (35 to 76 centimeters) long and weighing from 5 to 22 pounds (2 to 10 kilograms). "The body of a short-beaked echidna has dark fur almost completely hidden by a covering of hollow, barbless quills, called spines, on its back and sides," says Schwartz, "while long-beaked echidnas have little fur and more visible spines. The beige-and-black spines on all echidna species are about 2 inches (5 centimeters) long and help camouflage the echidna in the brush. They have very short legs, ideal for digging."

Found throughout Australia, Tasmania and New Guinea, from the highlands to the deserts to the forests, the short-beaked echidna is one of Australia's most widely distributed mammals. Here are 12 fun facts about this unusual critter.

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A wildlife care specialist at the San Diego Zoo Safari Park holds a four-month-old echidna baby — or puggle. The puggle — the first-ever to hatch at the San Diego Zoo Safari Park — was estimated to have hatched on Feb. 14, 2020.         Ken Bohn/San Diego Zoo Safari Park

1. They Dig for Their Food

These guys eat ants, grubs and termites, so digging for food is key. Areas with loose topsoil work well, although these animals can plow through hard-packed dirt as well. "Once an echidna detects its prey," says Schwartz, "it uses its long, sharp claws and short, sturdy limbs to dig into the soil and expose the invertebrates."

They also take advantage of a very strong sense of smell to locate their food underground or beneath wood or leaf litter, says Nicole Ellis, a pet expert and certified trainer with Rover.com. "It's believed that they use special cells in their nose that are sensitive to the electromagnetic signals of their prey—a sense usually associated with sharks," he says. "The unique sense is extremely advantageous when searching for colonies of insects."

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2. They Don't Have Teeth

Instead, they use their sticky, slender, long tongue to catch their food. "Hard pads at the base of the tongue and on the roof of its mouth grind food into a paste for swallowing," says Schwartz. Interestingly enough, he adds, the taxonomic family name for echidnas, Tachyglossidae, means "fast tongue."

3. They're Named After the Greek Mother of Monsters

In Greek mythology, Echidna was a half-woman, half-snake creature perceived to have qualities of both mammals and reptiles. She also was called the "mother of all monsters," because she birthed most of the mythical Greek creatures.

4. It's Hard to Tell Males and Females Apart

You can't simply determine an echidna's gender by looking at it, says Schwartz. "They have no gender-specific features, and their reproductive organs are internal," he explains. "Both male and females are born with spurs (which typically indicates a male), while females are meant to lose the spurs as they mature. Mating, of course, can establish a male from a female and DNA blood sampling can determine sex."

5. They Are Endothermic

That means they have the lowest body temperature of any mammal — around 89.6 Farenheit (32 degrees Celsius). "Their long-life spans — up to 50 years in managed settings — are due to their low body temperature and slow metabolism," says Schwartz. "Echidnas can enter an inactive state known as torpor, which is used by many animals to help them conserve energy. When in torpor, echidnas reduce their metabolic rate and lower their body temperature."

6. They Host the World's Largest Flea

The short-beaked echidna serves as a host to the echidna flea (bradiopsylla echidnae). It's thought to be the world's largest flea, reaching 0.5 inches (1.3 centimeters) in length.

7. Their Mating Ritual Is Odd

Echidna breeding season is during July and August (winter in Australia), according to Schwartz. Now this is where it gets a little strange. "Male echidnas often line up behind a female, nose to tail, forming long trains, up to 10 echidnas long," he says. "These trains are the first part of the strange echidna courtship and mark the beginning of the breeding season. When the female is finally ready to mate, the males dig a trench in the ground around her. The males compete for mating honors by pushing each other out of the trench. The last one remaining gets to mate with the female. Male echidnas may also mate with hibernating females."

8. Males Have a Four-headed Penis

"During sex, two of the heads shut down while the other two grow bigger to fit into the female's two-branched reproductive tract," says Schwartz. "Echidnas alternate which heads they use when mating with different partners to improve their chances of becoming a father."

9. Babies Are Called "Puggles"

An adult female echidna usually lays a single, leathery egg once a year, according to Schwartz. "She rolls the newly laid egg, about the size of a grape, into a deep pocket (or pouch) on her belly to keep it safe," he says. "Ten days later, the baby echidna, called a puggle, hatches. It weighs only about half as much as a miniature marshmallow! The puggle uses its tiny, see-through claws to grip the special hairs within the mother's pouch. The mother does not have nipples the way other mammals do. Instead, the little puggle laps up milk that the mother's body secretes from special glands in her pouch.

"Fortunately for the mother, the puggle does not yet have spines sticking out," adds Schwartz. "It remains in the pouch until its spines begin to break through its skin, at about 53 days. Then the mother puts the puggle into a burrow, where she returns to feed it every five to 10 days, until it is big enough to go out on its own at about seven months old."

10. Their Spines Are Actually Hair

The spines — made of keratin (or long, tough, hollow hair follicles) — are an echidna's main line of defense when predators strike. "If an alarmed echidna can't run away or hide, it curls into a prickly ball to protect itself or digs itself to safety," says Schwartz. In addition to being covered in spines, echidnas also are clad in shorter fur to keep them warm.

11. Males Also Have Spurs

"These are not venomous," says Schwartz. "Scientists have discovered that male echidnas use the spur on their hind leg to communicate with other echidnas, unlike the platypus, who use their leg spur as a weapon."

12. You Can Pick Up an Echidna, But Carefully!

While you should never pick up or disturb a wild animal, says Schwartz, echidnas can be picked up, when necessary. "It is recommended to wear thick leather gloves when handling an echidna, to protect your hands from their spines," he says.

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