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10 Curious Facts About the Platypus

Australia is typically known to be home to terrifying, dangerous, and life-threatening animals along the lines of deadly snakes, deadly spiders, deadly fish and so on. Australia, however, is also home to one of the worlds most bizarre and eccentric animals: the platypus. It’s the size of a small house cat, with the bill and webbed feet of a duck, and the tail of the beaver. You would think those characteristics alone would be enough of a reason for scientists to think the creature was a hoax, but the platypus is actually so much more absurd than you think.

They Don’t Have Stomachs

For most animals, including us humans, having a stomach is vital. The stomach plays a large role in the digestive system, being responsible for secreting enzymes which breaks down proteins to ensure maximum nutrient absorption can occur, as well as producing strong acids essential in softening food to help let the enzymes get to work. This organ’s first evolutionary appearance occurred 450 million years ago only in creatures with both a jaw and a backbone.[1]

So why does the platypus that has both a jaw and a backbone not have one? And how do they cope without one? The Platypus’s gullet connects directly to its intestines, completely bypassing where the stomach should have been. It is likely that the Platypus genetically lost its ability to have a stomach as a result of its ancestor’s diet consisting of shellfish and corals, both which are rich in calcium carbonate, which is very effective in neutralizing stomach acid. Because this substance can neutralize the stomach acid so effective, having a stomach simply become unnecessary. The platypus copes with not having a stomach, by relying on its intestines to do most of the breaking down, and absorption work.[2]

They Used to Be Giant

Platypus’s today are about 15 inches long, a mere fraction of the size they use to be. In the last decade, scientific discoveries were made, revealing that platypuses that lived about 5 to 15 million years ago were 3 feet long. That’s two-and-a-bit times bigger than their modern counterparts. This revelation was based on a single tooth from a distinct platypus beak discovered in a limestone fossil and thrown into a cupboard thinking it wasn’t anything exciting.

Years later Rebecca Pian, a Ph. D. student at Columbia University in New York City took them out of a cupboard in Australia’s University of New South Wales in 2012. Upon looking at the beak, Pian thought “Not only is it quite big, it’s quite different as well” as though the beak had the unique shape known to platypus’s, but also had never before seen bumps and ridges, as well as the much larger size. It was revealed that this ancient platypus belonged to a group of mammals called “monotremes” of which only three modern species is remaining: the platypus, and two species of echidna.[3]

Female Platypuses Don’t Have Nipples

Despite being mammals, female platypus’s lay a clutch of 1-3 leathery eggs rather than having a live birth. One thing mother Platypuses have in common with other mammals is that though they don’t have live births, their offspring still drink milk produced by the mother. However, instead of the young drinking milk from its mother’s nipples, the mother’s milk just oozes from her skin, much like how humans produce sweat. This “sweat” is also only oozed from the mother’s stomach.[4] As this delivery method is particularly unhygienic, as platypus are aquatic animals, the platypus does have some mechanisms in place to ensure the safety of her offspring. Nipples are considered a guard against bacterial contamination to the milk, so instead, the platypus developed a strong anti-bacterial protein to ensure their milk remains safe for consumption.[5]

They Use Gravel as Teeth

Since they don’t have a stomach, they need to mash up their food before it reaches their intestines to ensure the food is digestible to ensure nutrients can be absorbed, this, however, poses a problem as they also don’t have teeth. Their ancestors may have, but they also lost this evolutionary trait as time passed. Modern platypus’s instead use gravel as well as their grinding plates, essentially the equivalent to human using dentures. The scoop gravel (or even dirt) from the bottom of the waterbed to mash their up any food they had caught.[6]

Their Tail Doesn’t Have a Typical Purpose

People often compare the tail of a platypus to the tail of a beaver, who uses their tails to propel them through the water while swimming, but also to build dams and even to slap the water and scare off predators.[7] Its use to a platypus? To store fat, and for the mothers to hold her eggs against her warm body. Despite its minimal usages, the tail is essential to the animal, and who could picture a platypus without one anyways?

They Are Venomous

Though their small house cat size, beak, and tail makes the platypus look oh so loveable and cute, they pack a deadly punch. Both male and female platypuses are both born with a venomous spur on both of their hind legs, the female’s spurs, however, falls off before she reaches adulthood. So, to avoid the excruciating pain that could last for weeks, it’s probably best to avoid any wild platypuses you come across since you wouldn’t know if it was male or female until it was far too late.

The platypus is an anomaly of the animal kingdom, straddling the three classes of mammal (has fur and feeds its young milk), bird (has a duck-like bill and webbed feet), and reptilian (as having venom is typically a reptilian or amphibian trait). But why would the relative docile animal need to have venom? Well, platypuses have only a few predators: carpet snakes, eels, and foxes, so harboring this deadly toxin isn’t typically used in defense against predators. Researchers have deduced that the likely reason for the platypus to have such a deadly characteristic is to use it offensively during mating season. Don’t worry; researchers claim the venom isn’t used with the intent to kill fellow platypuses, but rather just to rouse a fight.[8]

A Lot of Scientists Didn’t Think Platypuses Were Real

In 1799 a platypus was taken from the burgeoning colony of Australia to British naturalist George Shaw and did not believe in it at all, even after seeing the carcass in person. In fact, Shaw was in such disbelief he grabbed a pair of scissors and went to work looking for the stitches that attached the bill to the pelt.[9] Now, during the 18th century it was popular for small businesses to graft pieces of different dead animals together, creating something along the lines of what Frankenstein was going for, take a look at Jenny Hanivers for instance. Fishermen towns drastically modified the bodies of rays or skates and claimed them to be demons, dragons, and even mermaids. And honestly? If I didn’t live in 2019 where the power of social media is strong, and I can google millions of pictures and videos of the strange mammal cross-reptile-cross-bird creature, I’m not sure I would believe in it either.[10]

They Use Electroreception

These odd creatures also don’t hunt down their food in a typical way, using their eyes and maybe even sense of smell, or hearing, but no, platypus use electroreception. It took a lot of convincing to make fellow scientists believe that the existence of platypuses wasn’t just some elaborate prank, and when they finally did believe they were left even more perplexed when they discovered the bizarre hunting method. Sir Edward Home explained that the nerves responsible for supplying sensory stimuli to the brain from the face teeth and tongue were uncommonly large, essentially making the bill of the strange animal susceptible.

In the 20th century, this notion was expanded upon, claiming that the unusual bill was a cleverly and intricately orchestrated mechano-and electro-sensory organ that can determine the exact location of deep-sea prey. This “bill sense” allows the platypus to navigate and hunt through light-limited areas accurately. It is believed that the pores on the skin of the bill demonstrated morphological similarities to the ampullary electroreceptors in electric fish. These receptors permit response to low-frequency electric signals produced but the nerves and hearts of animals.[11]

Platypuses Have 5 Pairs of Sex Chromosomes

Humans only have one pair, so why on earth do these eccentric creatures need five? In fact, five pairs of sex chromosomes break the record for the largest number found in mammals thus far. In total humans have 23 pairs of chromosomes, and yet platypuses have 26 pairs, which goes to show how complicated of a creature that is. For the longest time researchers had been confused over which chromosomal pairs were inherited equally by males and females (autosomal) and which were responsible for determining the animal’s sex, and then they were even more confused when they discovered that five pairs were all necessary for sex selection. We already know that the platypus has some of the characteristics of a bird, seen in its webbed feet and bird-like bill, but what you may not know is that the platypus may be the link that connects the evolution of bird sex chromosomes to mammal sex chromosomes.

Previously, it was believed that though both bird and mammal sex chromosomes evolved from autosomal chromosomes, it was thought that since they evolved from two different pairs, in two different classes that they evolved separately. The platypus puts this into question. Human sex is determined by one pair of chromosomes. The mother has two X chromosomes and the father has an X and a Y chromosome, so the combination of either the mothers X and the father’s X or Y determines if the child will be a female or a male, and this is similar to 1 of the 5 pairs of sex chromosomes found in platypuses. Another pair, however, resembles the ZZ/ZW sex chromosome system found in birds, thus making the connection between mammals and birds, and making a lot of scientists have to re-evaluate everything they thought they knew.[12]

They Have Three Eyelids

Yes, not one, not two but three. Now, to be fair to the platypus in this case humans may actually be the weirds ones, we only have 1, but many, many, many other species all have either two or three. This third eyelid is called the “nictitating membrane” which is an eyelid that moves horizontally across the eye, from the inner corner to the outer. Once upon a time, humans did have this trait, but all we have left of it now is a small structure just visible where the upper and lower eyelids join in the inner corner.

So why do platypuses need to have this third eyelid? The primary function for having one is to protect the eye from damage inflicted upon catching prey (or in the platypuses case, fighting against other males during mating season). Another important reason for having one it to protect the platypuses eyes from viruses and bacteria it could catch while submerged, and above water the eyelid keeps the eye moist.[13]

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