Nature continues to amaze us. If there was not scientific evidence for a lot of things that happen in the animal kingdom, they would be easily dismissed as fiction. Take this for example. Shrimp have their heart in their head—literally! Or, that a tiny garden snail can have up to 14,000 teeth, and some other species of snails can have 20,000! Animals do a lot of crazy-sounding things that are beyond our imagination. Here are some extremely bizarre animal facts that are hard to believe.

1 The Greenland shark reaches sexual maturity when it is 150 years old and has the longest known lifespan among all vertebrates of 300-500 years.

The Greenland shark, found in the Atlantic and Arctic Oceans, is one of the largest living species of sharks having a centuries-long lifespan. They are known to grow at a rate of 0.5-1 centimeters in a year and are 2.7 to 6.5 feet in length. Before the radiocarbon dating of crystals in the lens of their eyes was done by scientists in 2016, their lifespan was a mystery. The scientists in this 2016 research studied 28 specimens and found that the oldest of the sharks in the study were born between 1504 and 1744 CE.

The Greenland shark reaches sexual maturity only at the age of 150 years. The females of the species are known to keep the eggs in their bodies instead of laying them in the soil on the ocean-bottom. These eggs hatch inside the body of the mother shark, a process known as “ovoviviparity.” The flesh of the Greenland shark is known to be toxic and can produce an effect of drunkenness if consumed, but in Iceland, it is fashioned into a dish named “kæstur hákarl.” To create the dish, the meat has to be treated, fermented, and dried. The dish is a delicacy in Iceland. (1,2)

2 The New Mexico whiptail lizard is an all-female, crossbreed species whose eggs grow without fertilization. Despite that, they engage in female-female courtships.

Through a process called “parthenogenesis,” the New Mexico whiptail lizard reproduces asexually and engages in a mating behavior with other females of its own species. The lizard courts other females because this action stimulates ovulation. The lizard is a crossbreed of the little-striped whiptail that lives in the grasslands and the western whiptail that is found in the deserts. The hybridization of these two species does not produce healthy males of the lizard, even though males are found in the parent species.

The 16.5- to 23-centimeter-long New Mexico whiptail lizards are fast-moving, diurnal, and insectivores. They are found in semi-arid areas, woodlands, grasslands, shrublands, and rocky areas of New Mexico, Arizona, and Chihuahua. (source)

3 A scorpionfly is an insect that impresses its mates by bringing them prey to devour. But some of the male scorpionflies are not great at trapping prey, so they imitate females and wait for the other males to get them the prey. Then they fly away with the gift to give it to an actual female.

The way scorpionflies mate is very unique. The male scorpionfly hunts for an insect. It then tastes it, and if it finds the taste to be satisfactory, it will then hang it from a leaf of a twig inviting a female scorpionfly to eat the insect. While doing so, the male scorpionfly emits an odor which can be picked up by female scorpion flies from nearly 40 feet away. The female scorpionfly would then fly to the male, lower its wings, and eat the prey as a signal of acceptance. If the female does not like the prey, she would fly off. If she stays, they mate.

But there are some male scorpionflies who are masters at deception. They will imitate the female fly’s wing lowering and abdominal movements to steal the prey that is hunted by other male flies, and then present it to an actual female. Research has shown that such imitators have a higher rate of success (22%) at mating than those who do their own hunting (14%). Unfair as it may sound, this practice of transvestism is common in other species too. (source)

4 The two-toed sloths, who are known for their slowness, mate in just five seconds.

Dubbed as “the world’s slowest animals,” sloths are known to spend most of their lives lazying around and hanging upside down from the branches of a tree. If they move, they get no farther than around 125 feet in one day. But when it comes to mating for the two-toed sloth, the entire process is done in five seconds! The mating begins when a female sloth lets out a shrill scream to express her readiness. If there is more than one male suitor for her, they fight each other by hanging upside down on the trees and swiping at each other.

They mate between the months of September and November, and like most other processes, mating also occurs while hanging upside down for the sloths. Even the birth of two-toed baby sloths after a gestation period of around ten months occurs while hanging upside down. (1,2)

5  According to a study conducted on the farms in Oxfordshire, ostrich farmers had a hard time getting some ostriches to mate with each other because the birds are more attracted to humans than their own species.

Some “confused” ostriches get sexually attracted to human beings more than they do to other ostriches on ostrich farms. A study conducted by Dr. Charles Paxton, a statistician and ecologist found out that the birds were directing their courtship behavior at humans. This proved as a great challenge for the ostrich farmers who had a hard-time getting ostriches to lay eggs. The study that was conducted in Oxfordshire’s ostrich farms during the ostrich farm boom of the 1990s, observed that when human beings were not around, the sexual arousal levels of the ostriches dropped considerably. Also, it was observed that their mating patterns called the “kantling behavior,” where the males dropped their knees to the ground, puffing their wings out and making a booming noise, happened in the presence of humans and not otherwise. The ostriches who were reared in zoos with other ostriches did not show this behavior but the ones who were reared on farms in the presence of humans did. (1,2)

6 There lived a human-sized penguin in the ancient Paleocene period. It could look us in the eye and box as a heavyweight.

After the 55- to 59-million-year-old skeletal remains of ancient penguins were found in New Zealand, some were surprised that the adorable penguins could have once been intimidating creatures. The penguins that lived during the Paleocene period could be as tall as 1.77 meters ( 5 feet 11 inches) and weigh around 100 kilograms (220 pounds), qualifying them to box as a heavyweight. They are called “Kumimanu biceae.” In the Maori language, “kumi” means “a large mythical monster,” and “manu” means “a bird.”

Scientists have stated that the bird would have had a longer beak than the penguins today and would have been brown in color and not black and white. In contrast to the current cold habitat of the penguins, these ancient penguins would have lived in subtropical climates. Scientists have theorized that one of the reasons for the disappearance of these penguins could be the rise of marine mammals like sea lions and seals who competed for food, and predators like the toothy whales who hunted them to extinction. (source)

7 The mysterious narwhals’ “horn” or tusk is actually an overgrown, canine tooth. Some narwhals have two “horns.”

Many believe that narwhals are mythical creatures. For hundreds of years now, the narwhals have sparked curiosity among explorers and scientists. These shy creatures live in the Arctic’s frozen waters which makes them very difficult to study. They are famous for having a horn or a tusk on their heads. Many people thought the tusks to be a “unicorn’s horn.” These two- to three-meter-long tusks are actually overgrown canine teeth. The sea creatures do not have teeth in their mouths.

More males are known to have the tusks than females which suggests that the function of the tusks could have something to do with mating. Some narwhals are “double tuskers” with two such teeth on their heads. They do not use the tusks as spears for hunting. The use of these tusks is a mystery to mankind.

In a 2014 study, it was found that the tusks were highly sensitive organs which were soft on the outside and hard inside. The study suggested that the tusks were giant sensors of a kind with sensory nerve endings which could sense the changes in the salinity of the water. It has also been suggested that the tusk could be multi-functional. (source)

8 The only known animal that can become the replacement of an entire organ is Cymothoa exigua. It severs the tongue of a fish and then becomes its new tongue. It can also change its gender.

Found in the waters of the southern Gulf of California to the northern Gulf of Guayaquil, Ecuador and in the Atlantic Ocean, Cymothoa exigua (C. exigua) is a dangerous parasite. It enters a fish’s body through its gills after which the male attaches itself to the arches beneath fish’s gill, and the female attaches itself to the fish’s tongue. This 8- to 29-millimeter-long parasite severs the blood vessels of the fish’s tongue using its claws causing it to atrophy from lack of blood and eventually making it fall out of the fish’s mouth. C. exigua then becomes the fish’s new tongue and feeds on the fish’s blood and mucus to survive until the fish dies. When the fish dies, it detaches itself and hangs on the outside of the fish’s body.

Another striking feature of this parasite, aside from it being the only known one to replace an entire organ of a creature, is that its male undergoes a gender change voluntarily. It can turn into a female once it becomes 10 millimeters long. C. exigua is not believed to be harmful to humans as of now, but if the parasite is picked up alive by a human, it can bite. It is a shocking fact that isopods like C. exigua are often found attached to aquatic animals and often consumed by humans. (source)

9 The elephant’s closest living relative is the rock hyrax, a small furry animal.

What would come to your mind when you think of an animal that is the elephant’s closest living relative? Something as huge as the elephant itself, or an animal that comes somewhere close? Probably, but it is really a rabbit-sized animal called as the rock hyrax. It is found across sub-Saharan Africa except in Madagascar and in the Congo basin. It only weighs around four kilograms. The herbivorous rock hyrax and the elephant both belong to the ancient Tethytheria clade of mammals. During prehistoric times, the elephant and the rock hyrax descended from two different paths of evolution which is why they are so drastically different. They continue to have some similarities like tusks that grow from their incisors, some similarities in their reproductive organs. and flattened nails on the tips of their toes. (1,2)

10 Wombats poop in cubes. They produce 80-100 cubes of poop in one night.

Wombat poo is cube shaped so they can mark their territory with it but no one knows how they make their poo square #advancedwombattechnology pic.twitter.com/fIvMhyRoWS

— Diana S. Fleischman (@sentientist) November 3, 2016

Scientists had not yet unraveled the mystery behind the cubed-poop of wombats. The wombats are known to leave behind heaps of poop-cubes outside burrows and on top of rocks as a form of communication with other wombats. It has been theorized that this could be a way of marking territory or that the poop plays a role in mating. To find out why was their poop is shaped like that, the scientists at the Georgia Institute of Technology studied the digestive tract of wombats. It was found that cubes were formed in their intestines before excretion, and they were about two centimeters in length. The wombats take around two weeks to digest their food. The walls of the intestines of the wombats stretch unevenly—some parts are stiffer than the others—allowing for the creation of the cube shape. This is a unique trait in the animal kingdom. (source)