10 Animals With Incredibly Bizarre Biology


Some days, we as humans can find even our own anatomy a little perplexing. The extra bumps and ridges, the body parts you don’t even think about until they start acting up. If someone were to go from considering that to these animals, their head would really begin to spin. In the cases of the animals, head spinning is closer to a literal biological ability. 

We’re not going to neglect any class of animal here. It’s not just going to be strange bugs with an anatomical gimmick. We’re going to see birds, mammals, and other classes of animals that are much more familiar to us. Strangeness exists in every corner of the animal kingdom, even where we least expect it. 

10. Long-Wattled Umbrella Bird

Of the birds that have very distinctive and elaborate plumage, there’s usually something aesthetically pleasing about it. Peacock tails have that lovely fan effect, the flamboyant dance of a bird of paradise. This bird native to the Pacific Slope of the Andean Mountains found largely in fruit trees, however, looks like a caricature come to life. After all, the birds average from 15 to 20 inches long while the wattle has been measured at 11 inches long. And yet to attract mates the male flairs out the feathers on the wattle more, meaning it wants all the attention it can get to this aspect of its anatomy. 

Unfortunately for fans of front heavy birds, this South American miracle is endangered in Ecuador and has been since 2016, with fewer than 20,000 of them left in the wild. It’s due to their habitats being heavily deforested, rather than jealousy over its fabulous wattle. Fortunately habitats such as the Monteverde Cloud Forest Preserve have been set aside to protect their survival. 

9. Platypus

The platypus is now famous for being so unusual as a creature that when it was first sent to Europe in 1799 a number of scientists and intellectuals such as George Shaw thought it was a hoax. From its unusual duck bill to the fact it’s one of the few mammals to lay eggs, that’s an understandable reaction, though now those things are almost taken for granted about it. Much less well known is that it is one of very few mammals that is venomous. It has a poisonous barb unusually positioned in its hind heel. 

The venom isn’t used for hunting or self-defense from predators. You can probably guess what it’s used for just by being told that only males have it. Yes, you got it: during mating season it’s used by males while they grapple — though they have also been known to use them on humans that grab them during mating season. If this leaves you disillusioned with the creature’s adorable quirkiness, there’s at least the consolation that there are no reported human deaths from platypus venom. Still, it is an extremely painful experience that painkillers are completely ineffective against, so it’s not to be taken lightly. 

8. Mantis Shrimp

The earliest known report of a mantis shrimp dates back to 1817 and came from the Adriatic Sea, so it took 196 years of knowing about this species before a singularly advanced, almost impossible to imagine aspect of this creature’s body became common knowledge in 2013. While human eyes have receptors that can only determine three different colors on a spectrum (red, blue, green) and birds’s eyes seem much more advanced in that they have four different receptors and thus can see ultraviolet light, mantis shrimp eyes have sixteen. In addition to that, they have three pupils per eye, which aids in allowing each independent moving eye to have depth perception.   

When this first became a widely known fact about the mantis shrimp, it was inaccurately reported that because of the larger variety of color receptors in their eyes that the shrimp must be able to see a more colorful world that humans. In 2018, publications such as The Atlantic corrected this to clarify that mantis shrimp can’t actually see colors very well; what they can see is the polarization of light. This means their vision is less psychedelic color patterns and more high-contrast night vision, which is not only imaginable but has been simulated. However, as biologists pointed out, mantis shrimp eyes are the only ones in the world that can see “circular polarization” of light, so they remain bizarre in that way. 

7. Ribbon Worm

This genus of worm contains over 900 species which range in length from an average of eight inches to longer than 100 feet. Some of them are poisonous, and many of them are unique among worms for having distinct genders instead of all hermaphrodites. A number of them are poisonous. But it was in 2015 that most of the population learned, or at least saw, the most interesting aspect of them through a video from Thailand. 

In the video, a ribbon worm sitting in the palm of a man’s hand shoots a white substance from its mouth. It’s not just a short white appendage, it contains a number of branches from which smaller branches extend, as if the worm had shot white plant roots out of its mouth. (It’s also super gross.)

It turned out that the white branching substance was the creature’s retractable proboscis, and it was only trying to catch some food. These proboscises can be quite varied in surprising ways. For example, there is a green species of ribbon worms which shoot a pink proboscis out of their mouths, and which looks even more like a bit of silly string.   

6. Hagfish

This creature has been declared a delicacy in the Koreas and Alaska’s market for them has been expanding as of 2019. This, despite the fact the creature is basically a pile of oddities. Even if it weren’t, you’d think the fact it’s known colloquially as a “slime eel” would make it less appetizing. 

For one thing, the creature has four hearts in it and twice as much blood as most fish of comparable size. This massive amount of blood requires much more oxygen than normal, but fortunately the creature has fifteen sets of gills to supply it. Furthermore it has no spine, but it does have two brains, which is handy for a creature which has been known to literally tie itself in knots. As far as skin is concerned, it not only has the ability to absorb nutrients through its skin, usually by burrowing inside corpses. It’s skin is actually better for osmosis than its intestines are. 

But most of all is the slime. If it feels threatened, a hagfish is capable of releasing as much as 200 cups of slime in a second, which is a larger volume than many hagfishs’ bodies. How does it release so much? Well, the slime is reportedly 10,000 times softer than Jell-O, and so light as liquids go that it is massively compressed inside their bodies and expands incredibly in contact with water.   

5. Issus Coleoptratus

A species of planthopper insect, these are found in Europe and North Africa, so their existence has been known for a long time. Still, considering that they’re less than five millimeters long at their largest size (less than a fifth of an inch) no one can be blamed for not noticing its anatomical anomalies. It was in 2013 that it was first reported that this animal’s body offered the only known example of functional, interlocking gears in the animal kingdom. 

The gears are located on their rear legs, with between 12 and 15 interlocking teeth. They are used to ensure that the legs are fully synchronized and set for when it hops, and thus the insect has unusually well-aimed jumps. These wondrous gears are found only on the hindlegs of the young, being lost with a shed exoskeleton. Surely there are many people who’ve just entered the struggles of adulthood who can relate.   

4. Larvacean

Found throughout the world’s oceans, Larvaceans are essentially tadpole-like creatures usually less than four inches long. They’re noted as being solitary creatures. That’s not so surprising considering a thing that they do with their mucus. Over the course of 45 minutes, they will inflate a bubble often about three feet wide. It looks like a transparent indoor fast food restaurant playground that they stick their tails out of to locomote through the water. It’s essentially used as a giant net that guides objects small enough for the larvacean to consume to its mouth while oversized objects are kept stuck in the bubble. The bubbles usually get too clogged with food within about four hours and the larvacean has to abandon its expendable home and start blowing a new one. 

In 2020, after years of study by the Monterey Bay Aquarium Research Institute in California by bioengineer Kakani Katija, it was revealed that the bubbles are even more complex than they initially seemed. They also contain chutes to reduce drag, ribbed walls to aid the filtration, and curves of pipes. Meanwhile when was the last time you ever made something more complex than a bubble with your snot?  

3. Crystalline Mollusks & Garden Snails 

Humans can’t imagine what it would be like to have a rotating internal organ inside their torso, though it might feel that way after an authentic Mexican meal. Both of these bivalve invertebrates can boast such an implement for their digestive system. After their food is cut up in their mouths by a razor ribbon-like organ called a radula, it gets dragged into the stomach. The inside of the stomach is filled with cilla (essentially tendrils) that grasp the food as the stomach spins and pull it through the enzymes that further dissolve the food stuff. 

After a trip through the intestines for absorption of nutrients, it gets pushed to the anus. Unlike just about every other animal, the anus points not out behind the animal. No, it’s aimed over the back of the snail’s own head. The reason for this twist on regular anatomy is unknown.  

2. Barreleye

Imagine if your skull and scalp were transparent like the dome on Toy Story character Buzz Lightyear’s helmet. Well, if you’d like to encounter a creature that actually knows what that’s like you’ll have to go to the waters around New Zealand, Australia, or the Atlantic Ridge and dive down 2,500 feet to encounter a creature that actually knows what that’s like. Even as bewildering as this six-inch fish that was only discovered in 1939 is, appearances are quite deceiving. A 2009 study found it’s actually stranger than it appears. 

For one thing, those two points on the front of its face that look like baleful eyes are actually nostrils. The eyes are the two green domes inside what looks like its crystal skull. They’re in sockets that allow it to look straight up just as easily as forward, the angling allowing for better absorption of light from above, always a concern at that depth. If you were wondering, that transparent covering is indeed very fragile. When some samples of barreleye fish were caught for study, their skulls were destroyed in the process of bringing them to the surface and they survived only a few hours. 

1. Moray Eel

Everyone has some idea what a moray eel is, if for no other reason than Ursula’s hench characters in Disney’s The Little Mermaid. They’re put in the #1 spot for this list for hiding such a gobsmacking anatomical trick inside their bodies while being such commonly known creatures. It turns out these undersea beings that grow to an average of about four feet in length (though some have been found at a truly monstrous 13 feet) are closer to the xenomorph from the Alien movie series than anyone would have thought. 

Moray eels have a second set of jaws that they extend out of their main jaw during attacks called “pharyngeal jaws.” They’re not used for extra jaw strength or penetration power. They’re used to increase the suction of its bite and draw prey closer to its mouth, which is to make up for the fact that unlike most fish they can’t use fins on their sides to create a suction wave. As with so many things, it developed a monstrous aspect to compensate for a shortcoming.   

Dustin Koski collaborated on Return of the Living, a postapocalyptic ghost novel featuring perhaps the only creatures with anatomies stranger than those featured in this list.

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