Marsupials are Weird: The Science of Over the Edge

Marsupials are weird.

The "aliens" in Over the Edge are marsupial humanoids. Of course, the term "alien" is a relative term.

Marsupials are classified as mammals because they have four chambered hearts, warm blood and give milk. But unlike us placental-types, the two hemispheres of their brains are not unified--there is no corpus callosum which connects the two halves in placental brains. Double minded by design.

Marsupial eggs are more eggy than placental eggs because they retain a tiny egg yolk and a sort of soft egg shell through which the industrious sperm must penetrate.

In as little as 13 days after conception, marsupials give birth to barely there, practically transparent infants (blood red with black eye dot) who have only developed a couple of arms with which to climb. And climb they must from the opening of the birth canal (which incidentally is not the same canal through which the sperm was introduced) to the pouch, or marsupium, where they latch onto a nipple and remain for months.

Marsupium is Latin for "pouch." Funny how that works. Meanwhile, legend has it that the name "kangaroo" means (my paraphrase) "What the heck are you talking about?" The story went that early explorers asked the natives about the strange creatures hopping like frogs with deer heads standing upright like humans and the natives answered something they took to be "kangaroo" which was thought to mean..."What the heck are you talking about?" The story may not be true, but it should be.

Imagine the folks back home who heard about these creatures standing upright, as tall as a man, hopping around like frogs, many of which had two deer heads (a mother with a joey peering out of his marsupium)! People back home probably wondered what was in the drink.

The name, "gangurru," is from the Guugu Yimidhirr language. Captain James Cook and naturalist Sir Joseph Banks first recorded the name "kangooroo" or "kanguru" in 1770 when stopped at what is now, shock of all shocks, Cooktown, for repairs. Male kangaroos are called bucks, boomers, jacks or old men. Females are called does, flyers or jills. Babies are called joeys. A group of kangaroos is called a mob, troop or court. Click here for more about Kangaroos


Placentals have a things called a "placenta" which is the organ that protects the baby from his mother's immune system and links him to his mother through which he receives nourishment and oxygen and transmits his waste so the mother can get rid of it. Marsupials have placentas, the typically non-invasive chorio-vitelline variety. The placenta doesn't develop right away and are in use only two or three days. "Maternal recognition of pregnancy appears unnecessary in marsupials." Huh, yeah, I think that means marsupials don't ever realize they're pregnant, which might be a good thing since they are permanently pregnant.

Female marsupials have two wombs and three vaginas. The one in the middle is the one the joey uses to enter this cold, hard world and the two on either side are the ones the sperm uses to travel to the womb. (You may (or on the other hand, maybe not, be able to imagine how complicated the plumbing for the elimination of urine is given all this tubing.) Female marsupials can do this thing called diapause. The females can hold one baby in suspended animation while his sibling finishes developing in the marsupium. Or they can carry two babies at the same time one in each womb. And the males have forked penises, but when conditions are bad, males don't even bother to produce sperm. Kangaroos eat grass, but don't produce methane like cows do. Instead they transform the gaseous by-product into acetate which they use for energy.

Marsupials have the ability to see red, blue and ultraviolet. Yes, you read correctly, ultraviolet, one color which is invisible to us. But presumably they don't see green since they don't have what we recognize as the physical equipment for that. Exactly what they see, well, at present, nobody knows.

Many marsupials often don't even drink water. However, the yapok, the water opossum, living in Mexico, Central and South America, is the only aquatic marsupial in existence today. It's pouch faces to the rear and has a sphincter muscle which helps keep the water out. A yapok male also has a pouch where he keeps his genitals safe while swimming.

Marsupials can go into a state of torpor, kind of a mini-hibernation, that allows them to survive really chilly nights. Some marsupials go into torpor daily. The mountain pygmy possum can hibernate almost a year.

The above photograph was taken in the 1930's. The animal commonly called the "Tasmainian Tiger" is now believed to be extinct, though there have been rumors of strange "tiger" or cat-like animals lurking around livestock. Photo credit: Tasmainian Tiger

Why marsupials haven't developed more aquatic talents is probably explained by the marsupium which probably isn't as air tight as a developing baby would prefer. But cetaceans, that's whales, dolphins and porpises, are mammals that have many aquatic talents not the least of which is the ability to sleep with only half a brain at a time. See: specifically: "Cetacean sleep: An unusual form of mammalian sleep." Or Google: "unihemispheric sleep."

If marsupials could overcome the leaky pouch problem, then they could probably do the same trick since they are born double-minded anyway.

The marsupial humanoids of Over the Edge don't have ultra-violet eye sight, but they definitely are double-minded and have the strange genital features...er, let's move on to the next topic, shall we?