“X” is one of the least used letters in the English language, according to Grammarly.
However, the world is filled with animals and groups of animals that start with this rarely used letter.
These animals vary from ones that may live in your home to animals that no longer walk the planet.
1. Xoloitzcuintli
Xoloitzcuintli was a breed of dog that was considered to be the dog of the Aztec gods, and they are still loyal guardians of families today.
This breed is about 3,000 years old and comes in multiple variants, which include three different sizes and two coated types.
These dogs are known for being extremely affectionate with their families and always want to be a part of the action.
Because these dogs lack fur, they need to have sunscreen applied to their bodies before going out in the direct sun.
2. Xerus
Xerus is a genus of African ground squirrels, including the Cape ground squirrel, Mountain ground squirrel, and Unstriped ground squirrel.
A genus is a major subgroup of a family in the classification of organisms.
These ground squirrels can be found all over South Africa and spend 70% of their days feeding in the tall grasslands they call home.
3. Xantis Yak
The Xantis yak is a breed of domesticated cattle that is raised in the Himalayan Mountains.
Xantis yaks are descendants of the wild yaks that once roamed the mountain range.
They’re known for their long, thick coats and their unique color patterns.
The yak’s large heart and lungs help them withstand the high altitudes.
Their thick coat keeps them warm when the cold winds blow high in the mountains.
4. Xiphosura
Xiphosura is the order of horseshoe crabs, which include Atlantic horseshoe crab, Mangrove horseshoe crab, and the Chinese horseshoe crabs.
An animal’s order is a classification system of animals that is below class and consists of animal families that share similar attributes.
Xiphosura are made of two main parts, which include the prosoma and the opisthosoma.
The prosoma is the head, and the opisthosoma is the body that is made up of multiple plates which the crab uses to breathe.
5. Xuhai Goat
Xuhai goats can only be found in Jiangsu, China.
These goats were bred from the wild goats that live in southwest Asia and Eastern Europe.
They’re closely related to sheep and are ruminant animals, like the other members of the Bovidae family.
An animal’s family is the classification between genus and order, less precise than genus and more precise than the order.
6. Xerces Blue Butterfly
The Xerces Blue Butterfly was the first butterfly to go extinct in the United States and was last seen in San Francisco during the early 1940s.
As San Francisco expanded to fit the needs of the people, the development quickly chipped away at the butterflies’ home until they had nowhere to return to.
It was once considered common, especially when it was first discovered in 1852.
Out of the Xerces blue butterfly’s ashes came the Xerces Society for Invertebrate Conservation in 1971.
7. Xiphias Gladius
The xiphias gladius is best known as the swordfish.
These fish have been seen growing to nearly 15 feet in length, from the back of their tail to the tip of their weapon-like bill.
While young swordfish may have scales, adults will outgrow their scales and will eventually lose their teeth.
This means that the xiphias gladius must rely on its bill to lance its prey into bite-sized pieces.
8. Xenoposeidon
The Xenoposeidon was a nearly 30-foot tall dinosaur from the Cretaceous period.
The first xenoposeidon fossil was found in the 1890s by Phillip James Rufford in East Sussex, England.
However, the origin of the bone was uncertain.
The xenoposeidon wouldn’t be fully discovered until 2007, by paleontologists Mike Taylor and Darren Neish.
9. Xestochilus Nebulosus
The xestochilus nebulosus, or the nebulosus snake eel, can be found in the Indo-Pacific oceans.
They prefer to live somewhere with a place to hide, such as sandy or weed-filled ocean floors and tidepools.
Despite their scary appearance, they’re completely harmless to humans.
10. Xylophagous Leafhopper
The xylophagus leafhopper, also known as the glassy-winged sharpshooter, has caused massive trouble for the Temecula, California region.
They caused an outbreak of Pierce’s Disease in the vineyards of Riverside.
These bugs will drop into old leaves once winter rolls around and are able to survive temperatures as low as 20 degrees Fahrenheit.
11. Xiaosaurus
Xiaosauruses were smaller, herbivorous dinosaurs that roamed Earth during the Jurassic period.
On average, they were about five feet tall.
Due to their height, they preferred to eat low-hanging plants.
These bipedal dinosaurs were quick thanks to their long legs.
Xiaosaurus once lived where modern China is today and was named by Dong Zhiming and Tang Zilu.
12. Xenurus Unicinctus
The xenurus unicinctus is a beloved animal that is better known as the Southern naked-tail armadillo.
These armadillos spend 99.25% of their time underground and are rarely seen above ground.
The caverns they are able to create and expand in seconds have all the grubs, roots, and bugs that they could ever need.
Due to all their time in the dark, they have poor eyesight.
To make up for their lack of vision, they have excellent senses of smell and hearing.
13. Xenentodon Cancila
Xenentodon cancila is the scientific name of the Freshwater Needlefish, which can be found all over Pakistan, Nepal, India, Bangladesh, Myanmar, Thailand, and Sri Lanka.
They are most commonly found in ponds and small rivers.
These small, thin fish are only able to withstand still or slow-moving waters.
When monsoons strike, they may be found in the flooded areas.
14. Xeme
Xeme is the old name of the Sabine’s gull or the fork-tailed gull.
They are best known for their striped tails.
During their mating season, male breeding xeme will have darker feathers on the top of their head and face.
On average, these sea birds will live for 18 years and only weigh up to about eight ounces.
It takes them two years to grow in their adult feathers.
15. Xenotarsosaurus
The xenotarsosaurus was a bipedal carnivore that lived during the Cretaceuos period.
They once lived in what became Argentina and were discovered by Graciela Bochatey, Olga Giménez, Ricardo Martínez, and Jorge Rodríguez in 1986.
The only fossils we’ve found from the dinosaur are two anterior dorsal vertebrae and a right, hind leg bone.
16. X-Ray Fish
The x-ray fish is one of the coolest additions you can put in your fish tank.
The fish is incredibly translucent, except for its skeleton.
They’re native to the Amazon basin, but their popularity has led to them being bred as pets all over the world.
They can also be found in the coastal areas of Brazil, Guyana, and Venezuela.
These omnivorous fish eat larvae, worms, and aquatic plants.
17. Xenarthra
Xenartha is the magnorder that sloths, armadillos, and anteaters belong to.
Magnorders are the highest taxonomic ranking of order.
The similarities that all of those animals share comes from the lumbar vertebrae they all share, which is called the xenarthrous.
Animals of the Xenarthra magnorder have additional joints that help strengthen their hips and back.
18. Xinjiang Goat
Xinjiang goats are named for mountains where their breed can natively be found in China.
These mountain goats come in black, white, or brown and are most commonly raised for their milk, fur, and meat.
Xinjiang goats are known for growing thick, soft cashmere.
19. Xingxiulong
The Xingxiulong was alive during the Early Jurassic period.
They were over 16 feet tall and are believed to have been covered in more scales than feathers.
While their legs, arms, and nose were quite short, they had a long neck that they would use similar to a giraffe.
Instead of using their hands to put food in their mouth, they simply lowered their neck to the ground, despite being bipedal.
20. Xolmis
The Xolmis genus of birds from South Africa, including the Fire-eyed Diucan, Salinas Monjita, and the White Monjita.
These birds can be found in the open grasslands or wide-open pastures with scattered trees.
These silent birds prefer places near the water, where they can easily scoop up small prey.
They can be spotted by their nearly all-white bodies and black flight feathers.
21. Xami Hairstreak
The xami hairstreak is a beautiful butterfly that can be found in the southern part of the United States and all over Mexico.
Xami hairstreaks will lay their eggs on the underside of succulents, which the caterpillars will then eat through shortly after they’re born.
Although they are considered to be rare worldwide, they are quite common in southern Texas and Mexico.
They’re most commonly found in rocky canyons.
22. Xiaotingia
The xiaotingia is known as the first bird in history and was found in China in 1861.
Before the discovery of the xiaotingia, the archaeopteryx was thought to be the oldest bird.
These prehistoric bird ancestors were alive during the Bathonian, Oxfordian, and Jurassic periods.
Xiaotingias were tiny dinosaurs that were only about 23 inches.
23. Xilingol Horse
The xilingol was bred on the steppes of Xilinggral Meng in Inner Mongolia.
This horse was recognized in the 1960s, after being bred from a line of Russian Thoroughbreds, Akhal-Teke, Karbarda, Don, and Mongolian horses.
Xilingols have all the best features of each of the horses that they’re bred from.
They’re incredibly fast horses that are strong-minded and strong-willed.
They are loved for their beauty and their racing abilities.
24. Xenicus Gilviventris
Xenicus gilviventris is the scientific name of the New Zealand Rockwren, which is now considered to be an endangered species.
Although the xenicus gilviventris could once be found all over New Zealand, they are now only found in the South Island, in alpine regions of the island.
There are only 5,000 of these small, round birds left on the South Island, and their population is decreasing.
25. Xenoceratops
The xenoceratops is one of the oldest horned dinosaurs to ever be found in Canada.
The remains of this dinosaur measure out to be about 20 feet in length.
Researchers believe that the dinosaur could have easily weighed two tons.
The xenoceratops has shown prehistoric researchers that ceratopids have always had strange horns around their heads.
As the animals evolved, later descendants of the xenoceratops would go on to have even more elaborate horn designs.
26. Xucaneb Robber Frog
The xucaneb robber frog is a vulnerable species of frog that is on the brink of endangerment.
These frogs have lost their homes to deforestation caused by human settlement, the expansion of farmland, and logging.
Xucaneb robber frogs can be found in Guatemala and are more common in Sierra de la Cuchumatanes, Sierra de Xucaneb, and Sierra de las Minas.
27. Xinjiangovenator
Xinjiangogovenators were a genus of dinosaurs that lived during the Early Cretaceous period.
Their name means “Xinjiang hunter”, which refers to where they used to live and hunt for their prey.
Through the years, these dinosaurs have been mistaken for other dinosaurs, such as the phaedrolosaurus.
Unlike the phaedrolosaurus, xinjiangovenators have stronger, sharper teeth.
28. Xenorhyncus Asiaticus
The xenoryhncus asiaticus goes by many names, like the policeman bird and the jabiru.
However, it is best known as the black-necked stork.
This Australian bird can be found striding along floodplains and hunting for fish among the tall reed beds.
They also eat small crustaceans and amphibians as well.
29. Xalda Sheep
Xalda sheep have been bred for generations, starting as far back as 27 BC.
They are one of the oldest breeds of sheep in their homeland of Spain.
The Asturi tribe used to make their tunics with the wool of xalda sheep.
During the 18th century, there were 60,000 xalda sheep.
Over a decade ago, the breed was nearly extinct, with only 400 remaining sheep.
Thanks to preservation efforts, the population has grown to about 17,000 sheep.
30. Xolocalca Bromeliad Salamander
The xolocalca bromeliad salamander is an endangered salamander from Mexico that can only be found in one forested area near Chiapas, Mexico.
Their forests consist of pine and oak trees that are 6,000 feet above sea level.
The most coloration of the xolocalca bromeliad salamander is a shade of brownish lavender with a black marking on its head.
The other two colorations are a combination of a creamy pink and black.
31. Xinjiangtitan
During the Jurassic period, the xinjiangtitan was munching on the plants that grew in prehistoric Asia.
They’re best known for their extremely long necks and are known for having the longest preserved neck in all of history.
When adding up all the neckbones that paleontologists have found that belong to a single xinjiangtitan, its neck totals to just under 44 feet in length.
32. Xantusia Henshawi
The xantusia henshawi is another name for the granite night lizard.
These lizards can only be found in certain parts of California and a small part of northern Mexico.
Although they are in high demand among reptile fans, they are not allowed to be collected from their local area for the pet trade.
These lizards require exfoliated and fissured granite outcroppings in order to survive.
33. Xinjiang Ground Jay
Xinjiant ground jays live most of their lives on the ground and are known for their sand-colored bodies and their curved, black beaks.
Due to the black markings on their faces, many people think they look like they have mustaches.
These birds are incredibly fast runners and will chase their prey, such as reptiles and bugs, through the desert on foot.
For this reason, they like dry, open areas with places for them to perch and scope out the area.
34. Xiongguanlong
Xiongguanlong were Cretaceous period dinosaurs that were about the height of humans, despite being nearly 15 feet from their head to the tip of their tail.
This dinosaur was found in the Gansu province of China.
Despite having a long snout and being related to tyrannosauruses, the xiongguanlong has an incredibly slender head.
Most of this dinosaur’s fossil representation has been skulls and partial postcranial remains.
35. Xenopeltis Unicolor
The xenopeltis unicolor is a snake known for its smooth scales that shine brilliantly in the sun and can be as bright as a camera flash.
It is also known as the sunbeam snake or iridescent earth snake.
Its smooth scales make it easier to slither across muddy trains in order to catch small lizards and frogs.
On average, these snakes grow to be about four feet in length.
36. Xantus Swimming Crab
Xantus swimming crab is much different from other species of crabs, with rear legs that have broad paddles on the tips to help them swim better.
Along the sides of their bodies, they have extra long and sharp spines.
Xantus swimming crabs have no problem eating other crabs, with the smaller sand crabs being one of their favorite meals.
This crab will plunge its claws into the sand in order to find its prey.
37. Xanthippe’s Shrew
Xanthippe’s shrew is a small rodent that can be found throughout Tanzania and Kenya.
They’ll be hiding underground in dry savannas and subtropical or tropical shrubland.
These shrews love to eat mice, beetles, grubs, grasshoppers, nuts, seeds, and whatever vegetation they can find underground.
In order to have enough energy, shrews eat every three to four hours.
38. Xenosaurus
The xenosaurus, or xenosaurus platyceps, is an endangered species of lizard that can only be found in the Sierra Madre Oriental of Mexico, where they can enjoy dry scrub forests and oak savannah areas.
Xenosauruses are viviparous, which means that they give live birth to the baby lizards that have formed inside the mother’s body.
39. Xingu River Ray
The Xingu River Ray, which is also referred to as the polka-dot stingray in the United States, is named after the Xingu River Basin in Brazil.
The ray is black with bright, white dots all over its body.
On average, they are 18 inches in diameter.
They bury themselves under the sand during the day and come out at night to hunt.
Xingu River rays like to eat fish, crabs, and snails.
40. Xenopus Laevis
The xenopus laevis, or the African clawed frog, is unique from other frogs thanks to their lack of a visible tongue.
The males of the species also lack a vocal sac, which frogs use in order to croak.
While other frogs may have four webbed feet, the xenopus laevis only has two webbed feet and two unwebbed feet.
41. Xinjiang Donkey
Xinjiang donkeys helped save a small village in China from poverty and allowed them to create a booming business breeding the donkeys.
Although these donkeys were once bred for transportation and farm work, they are now bred for their milk.
Some of the villagers have even begun selling donkeys to neighboring towns and teaching them how to raise and milk the donkeys.
This has helped improve the lives of residents all over Xinjiang.
42. Xuthus Swallowtail
The Xuthus swallowtails are one of the few butterflies that are able to mate a few times within their lives.
Most butterflies and other bugs have such short lifespans that they don’t have the time or the energy to reproduce multiple times.
Thanks to the increased pairings of parent butterflies, there is more genetic diversity in these butterflies than most.
Xuthus swallowtails can be found all over Asia, including Japan, Taiwan, China, Myanmar, Siberia, and all over the Korean Peninsula.
43. Xantic Sargo
Xantic sargo are fish that are able to grunt by grinding their teeth together.
During the day, xantic sargo will hide among the rocks and in any other underwater structures they can find.
They come out at night to hunt crustaceans, bryozoans, and mollusks.
The pouty expression on their faces has earned the local name of Sweetlips.
These fish aren’t normally eaten due to their small size but have more popularity as gamefish.
44. Xenophthalmichthys Danae
The xenophtalmichthys danae is a deep-sea fish that can be found 4,100 feet below the ocean’s surface.
Their pencil-shaped bodies have tiny fins and a tail that is only slightly thinner than their body.
At their maximum length, they can only grow to less than 3.5 inches.
This species of pencil smelt can be found deep in the Gulf of Mexico and the Caribbean Sea.
45. Xiphophorus Maculatus
Xiphophorus maculatus is what scientists call the southern platyfish.
These freshwater fish are popular pets but have become an invasive species in 18 different countries due to people dumping their pet fish.
Originally, you could only find the xiphophorus maculatus in Mexico, Guatemala, Belize, and Honduras.
Despite them being invasive, most people don’t see them as pests thanks to their beautiful appearance.
46. Xenopterus Naritus
The xenopterus naritus, or the golden pufferfish, is known for being incredibly territorial and aggressive.
Domesticated golden pufferfish require their own tanks due to the amount of space they claim as their own.
Cases of this pufferfish tearing the other fish that live in their tanks are so common that experts recommend that you only fill the tank with fish that are faster or get a large aquarium.
47. Xingu Scale-Backed Antbird
The Xingu Scale-Backed Antbird is named after the Xingu River, which they live near in the southeastern part of the Amazon in Brazil.
These small birds communicate with a series of 10 different tweets that increase in pitch.
Males are gray with speckles and females brown with gray undersides.
48. Xuanhanosaurus
The Xuanhanosaurus is a massive carnivore from the Jurassic period that called Sichuan, China home.
There has only been one specimen that paleontologists have been able to find, and it was found in the Xuanhan County Sichuan Basin.
49. Xingu Corydoras
The Xingu corydoras may seem like a friendly fish, but these fish are hiding venom in the axillary glands at the base of each spine.
These freshwater fish are from the upper Xingu River Basin in Brazil.
Xingu corydoras are scaleless fish, making them incredibly sensitive to salt.
They’re nocturnal hunters that like to eat anything they can find on the basin floor.
50. Xixiasaurus
The xixiasaurus is a small dinosaur that inhabited China during the Late Cretaceous period.
Nobody is certain of the xixiassaurus diet, but most assume they were omnivores thanks to the lack of serrations on their sharp teeth.
They were about 3.9 feet long and likely stood at the same height as most humans.
51. Xenophallus Umbratilis
Xenophallus umbratilis may not seem all that impressive at first, but they are one of the species of fish that displays dominant handedness.
Similar to how people are born left or right-handed, the male xenophallus umbratilis has a dominant side that their anal fin leans toward.
Studies have shown that whichever way their anal fin leans is the opposite side that the small fish will look out for predators or potential mates with.
52. Xeniades Swallowtail
The Xeniades swallowtail is a beautiful butterfly that can be found in Peru, Ecuador, Colombia, and southern Bolivia.
However, some people call them the cattleheart mimic.
These butterflies have a toxic quality that comes from the plant they eat while they’re still caterpillars, the aristolochia.
This keeps predators from eating their young or adult butterflies.
53. Xantus Becard
Xantus becard is a bird of many names, including the larger becard and the rose-throated becard.
Only the males have the red plumage around the front of their throats.
Females are light brown with gray plumage on top of their heads.
54. Xiurenbagrus Dorsalis
The xiurenbagrus dorsalis is one of the newest members of the xuirenbagrus genus, which is made up of a few species of catfish.
This cave-dwelling catfish was found in the Pearl River and doesn’t have eyes, making it the first record of a blind catfish in China.
55. Xantus Leaf-Toed Gecko
Xantus leaf-toed gecko can be found in the Baja California Peninsula and other surrounding islands.
Their leaf-like feet help them plenty in with the shrublands that they like to call home.
Like other species of geckos, they are to lose their tail when scared.
These skittish creatures squeak when they feel like they’re in danger.
56. Xeric Ambersnail
The Xeric Ambersnail can be found in the grassy hillsides all over the eastern half of the United States and in some parts of Canada.
They have extremely thin shells that have an amber glow.
Xeric ambersnails are extremely common and easy to find in your backyard if you live in that part of the country.
57. Xylocopa
Xylocopa is the genus of large carpenter bees.
The name of the genus comes from the Greek word for “wood-cutter”.
Although they may appear soft and fuzzy like bumblebees, larger carpenter bees have naked lower abdomens.
Because of how much nectar carpenter bees take from flowers, they are referred to as nectar robbers.
58. Xixiposaurus
The xixiposaurus is a newer dinosaur that was found in 2010, in Yunnan, China.
They lived during the Jurassic period and are considered to have been omnivores.
The dinosaur is named after the town it was discovered in, Xixipo.
So far, paleontologists have found only one specimen.
59. Xanthostigma
Xanthostigma is a genus of snakeflies that can be found all over Europe.
They’re called snakeflies due to their long bodies and extended ovipositor that only the females have.
The ovipositor is the needle-shaped organ some female bugs use to deposit their eggs.
60. Xestus Sabertooth Blenny
The xestus sabertooth blenny lives a solitary life and never strays far from its burrow in shallow, weedy waters.
These omnivorous fish use their large teeth to eat small crustaceans, fish scales, diatoms, mucus, and algae.
Xentus sabertooth blenny will eat the scales off of fish that are swimming around.
61. Xavier’s Greenbul
Xavier’s greenbul is a brightly colored bird that can be found in the rainforests of Africa.
Due to how similar they look to Icetrine greenbuls, the two species will often form mixed-species flocks.
The only way you can tell the two species apart from a distance is their calls and slightly larger bills.
62. Xyrias
Xyrias is a newer genus of snake eels that consists of only four different species, some of which are so new that they haven’t received common names, such as the xyrias chioui and the xyrias guineensis.
The Strict snake eel and the Speckled snake eel are also members of this genus.
Similar to snakes, these eels eat their prey whole.
Domesticated snake eels may even eat out of their owner’s hand.
63. Xuanhuaceratops
The xuanhuaceratops is a tiny dinosaur that was only a little less than three feet in length, from the end of its snout to the tip of its tail.
They had beak-like mouths that were perfect for tearing the leaves on branches during the Late Jurassic period.
64. Xenocrates Leafwing
The xenocrates leafwing is a butterfly that you can find in Bolivia, Brazil, and Colombia.
They rarely leave the canopies of the Amazon rainforest.
Males have a blue tint to their mostly black wings, while females can be identified by the orange tint and markings on their wings.
65. Xenopirostris Polleni
The xenopirostris polleni, or Pollen’s vanga, is native to Madagascar and is known for its unique set of calls.
Most of the time, they will communicate in whistles, but they will scold other birds with a call that sounds like “che-che-che”.
66. Xantus Murrelet
Xantus Murrelets have the largest parent to egg size ratio to any other bird in the world.
Their eggs weigh 25% of the mother’s weight.
Due to an increasing cat population in their home of the Baja Peninsula, the species has come under threat.
67. Xanclomys
The xanclomys is a small rodent that lived in the Paleocene period of North America.
The Paleocene period began after the Cretaceous period and is historically marked by the major extinction event that wiped out many prehistoric species like the dinosaurs.
68. Xyliphius
Xyliphius is a genus of banjo catfish that can be found in South America.
There are seven different species of banjo catfish in this genus, with the newest one being found as recently as 2017.
The xyliphius sofiae is the newest member of the genus and is completely blind.
69. Xenomys Nelsoni
Xenomys nelsoni is a species of rodent that is found off the Pacific Coast of Mexico.
These nocturnal hunters live in dense tropical forests and use their surroundings to their advantage.
Traveling the forests, these rodents move along tree branches and make spherical nests to rest during the day.
These rodents are surprisingly clean and create their own burrows for excrement.
70. Xantus Hummingbird
Xantus hummingbird is a subspecies of hummingbird only found in the Baja California Peninsula.
This bird prefers scrubby forests and tropical environments.
Food is plentiful for Xantus hummingbird, being able to lick nectar from plants at about 13 licks per second and catch bugs on its own wings.
71. Xenacanthus
Xenacathus is a prehistoric shark that has had fossils found worldwide and can be traced back as far as 306 million years ago.
hese sharks heavily resembled modern eels and had an elongated spike, which could have been venomous, atop their heads.
It is likely the Xenacathus fed on smaller fish and crustaceans because they were only approximately one meter long.
72. Xixianykus
Xixianykus is a genus of dinosaur that comes from the Henan province in China.
Though the size of this creature may seem small, standing about 7.8 inches tall and 19.6 inches in length, its best survival tactic was its speedy hind legs.
73. Xenoclea Longwing
Xenoclea Longwings are venomous butterflies that possess ultraviolet vision to help distinguish between different butterflies in search of a mate.
Unlike other butterflies, they eat both nectar and pollen.
Recent studies have shown that their saliva may carry a type of specialized acid to aid in the breaking down of pollen for nutrients.
74. Xenodermichthys Nodulosus
The Xenodermichthys Nodulosus, the scientific name of one species of slickhead, is a fish that has no scales and has instead thin skin.
They are most commonly brown and have large, white, eyes.
They can be found in waters near Japan and the Philippines.
75. Xenoceratops
The Xenoceratops was an herbivore that ate with a bird-like beak at the end of its long snout.
A xenoceratops’s crown at the back of the head had two large horns and two more above the brow.
The fossils of dinosaurs were found in southern Alberta, Canada.
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