Short-beaked echidna. Photo: Jeroen Visser/Shutterstock
Quick: what mammal is covered with spikes, lays eggs, has a four-headed penis, and no nipples?
The answer is the echidna, one of the strangest animals that exist on Earth today. And to celebrate this bit of mammalian weirdness, here are Neatorama's Five Fascinating Facts about Echidnas:
1. Echidnas Can Control Their Spines
Echidnas are covered with fur and spiky spines. These spines are modified hairs, similar to that of the porcupines. There are tiny muscle bundles connected to the base of each spine so the echidna can control the spine's movement and direction.
Short-beaked echidna curled up into a ball of spikes. Photo: Nachoman-au/Wikipedia
An echidna erects its spines for protection (like the picture above), to anchor itself against a log, to help it climb, and to help upright itself after it has fallen or placed on its back. It cannot, however, throw or eject its spines as the legend said.
2. Baby Echidnas is Called a Puggle and It's Incredibly Cute!
Photo: Anthony De Zoete-Baker/Australia Zoo - via ZooBorns
A mom echidna lays a single leathery egg in her pouch, then carries it for about ten days before it hatches. The baby echidna, called a puggle, is born hairless and spineless - but with formidable claws.
As the puggle grows, it develops its covering of fur and spines. After two months, its mom would evict it out of the pouch, because, you know, it's not fun carrying something with spiky spines in your pouch.
More puggle cuteness: this one named Beau the orphaned echidna is from the Taronga Zoo:
Photo: Ben Gibson/Taronga Zoo - via ZooBorns
3. Echidnas Don't Have Nipples
Female echidnas produce milk, but they have no nipples. Instead, they secrete milk in two small, hairy areas known as aerola patches, which are connected to the milk glands. A baby echidna suckles milk straight out of its mom's skin.
4. Male Echidna has a Four-Headed Penis
You read that right. Male echidna has a four headed penis. During mating, two of the heads shut down and the other two are used to ejaculate sperms. A male echidna would swap which heads are shut down and which are used to inseminate the female each time the animal copulates. The echidna penis is somewhat prehensile - it can move about when erect (see the video clip below)
Oh, and male echidnas do not use the penis to urinate. It is solely used for mating. Instead both males and females have cloacas.
5. Super Sperm, Assemble!
As if a four-headed penis isn't bizarre enough, there's more to the echidna mating habit. You know you're seeing echidnas mate when you see a train of male echidnas "queueing" to copulate with a single female. In fact, when in heat, a female echidna could mate with up to 11 males one after another. (There's a bit more to this mating prowess - for example, echidnas can also mate underground.)
See also: 30 Strangest Animal Mating Habits
Mating with multiple males present a tremendous competitive pressure on the sperms to fertilize the egg. So echidna sperms do something very unusual: hundreds of individual sperms team up to form giant super-sperm bundles. These sperm bundles can swim much faster than individual sperms, and therefore present an evolutionary advantage.
Bonus Fact: Echidna is Named After the Greek "Mother of Monsters"
Echidnas are weird - they have a mish-mash of reptilian and mammalian features, which was recognized early on by biologists. In 1802, British anatomist Everard Home named the curious animal after the Greek goddess Ekhidna (meaning "she viper") who was half-snake and half-woman. She's the goddes "Mother of Monsters" because most of the monsters in Greek mythology were her offspring.
Bonus Fact: How Does Echidna Taste Like?
In 1792, the ship HMS Bounty*, captained by William Bligh, arrived in Tasmania on its way to Tahiti. Its crew discovered a strange creature with a "beak like a duck." Naturally, they shot one and ate it. The crew noted that "the animal was roasted and found of a delicate flavour." (Source: Echidna: Extraordinary Egg-Laying Mammal by Michael Augee, Brett Gooden, Anne Musser).
*Yes, this is the same ship that's famous for Mutiny on the Bounty in 1789.
In 2007, scientists had feared that a species of Attenborough's long-beaked echidna (named after the famous naturalist Sir David Attenborough) had become extinct in New Guinea. But they were told by hunters that the echidna species was still around. These hunters knew because they had just eaten some and said "the meat was very greasy and extremely tasty."