Liger

A liger is a cross between a lion and a tiger. Which of these is the real thing?

In the wild, tigers roaming the savannahs of Tanzania and lions stalking prey in the jungles of Uganda wouldn't cross paths. Zoos and conservations, though, provide the opportunity to mingle. The lovechildren of lion fathers, Panthera leo, and tiger mothers, Panthera tigris, are called ligers. Ligers sport both the golden fur of the lion and tiger stripes down the length of their backs. Unlike water-shy lions, they share the tiger’s love for getting wet, lounging for hours at a time in shallow water. Tigers are solitary animals and lions are social, so a liger’s personality depends on which cats they spend their time with—they get along easily with both species.

Ligers are also fertile, and very big. Male lions pass on genes that encourage their cubs’ growth, while female lions pass on genes that slow it down. Tigers don’t pass on these types of genes, so ligers can grow to twice the size of their parents. The largest liger in the world, Hercules, weighs 922 pounds.

All known ligers come from accidental cross-breeding in captivity—although it’s possible that in the past crossbreeding occurred in the wild, says Bhagavan Antle, director of The Institute for Greatly Endangered and Rare Species (TIGERS) in Myrtle Beach, South Carolina, and Hercules’s keeper. “Historically, there were vast areas where they had the opportunity to breed, so there must have been wild ligers,” Antle says. Other Panthera cats, such as jaguars and leopards, have bred with one another both in the wild and in captivity.

Grolar Bear

A grolar bear is a cross between a grizzly bear and a polar bear. Which of these is the real thing?

In 2006, a hunter in Canada’s Northwest Territory shot and killed a strange-looking polar bear that sported scattered brown patches, long claws, and a humped back. DNA testing of the animal revealed it was a hybrid, born from a polar bear, Ursus maritimus, and a grizzly bear Ursus arctos horribilis.

“Polar bears are in evolutionary terms relatively recent derivatives of grizzly bears,” says Brendan Kelly, associate vice president for research and associate professor of marine biology at the University of Alaska. “It’s not uncommon for mammals that have diverged, if they come back into contact, they are capable of interbreeding.” In his 2A0 Nature paper, Kelly argues that as the arctic ice diminishes, polar bears spend more time on land, while warmer weather pushes grizzly bears northward. Because of this, the two species are more likely to cross paths.

Grolar bears look and behave more like polar bears, exhibiting specialized pouncing behavior: They rise up on their hind legs and come down hard on the ground, collapsing snow caves in which seal pups are born. However, they aren’t as adept at swimming as their polar parents, making them less fit for an arctic habitat.

Kelly finds the hybrid trend worrisome because the grizzly bear species could potentially absorb the already fragile polar bear species into their population. “If a species is becoming really rare, the chances of meeting a mate of their own species gets smaller and smaller,” Kelly says. “It can become the final death knell to a species if it’s really rare and surrounded by another species it can interbreed with.”

Wolphin

A wolphin is a cross between a false killer whale and a dolphin. Which of these is the real thing?

Marine dwellers get frisky with unusual mates, too. A false killer whale, Pseudorca crassidens, and a bottlenose dolphin, Tursiops truncates, that were kept together in a Sea Life Park in Hawaii, produced a female wolphin named Kekaimalu. Kekaimalu, who is now almost 30 years old, is the only known living wolphin today.

Dolphins are grey, and false killer whales are black with a light grey underbelly. Kekaimalu inherited the false killer whale coloring but her rostrum has a strong dose of the dolphins’ long snout; false killer whales have shorter ones. Her appetite is certainly whale-like—she can eat up to 80 pounds of fish and squid in a day, almost twice as much as a dolphin.

Kekaimalu’s keepers thought she wouldn’t be able to mother offspring, but to everyone’s surprise she birthed her first calf when she was only 5 years old—her parents have the same number of chromosomes (44), which increases her chances of being fertile. Since then, Kekaimalu has birthed three more. “Her gestation periods are a blend between a false killer whale and a dolphin,” says Jeff Pawloski, curator of Sea Life Park.

Cama

A cama is a cross between a camel and a llama. Which of these is the real thing?

Some animal hybrids were created on purpose, by humans. Breeders at the Camel Reproduction Centre in Dubai created a cama—a cross between a camel, Camelus dromedaries, and a llama Lama glama, both members of the same family, Camelidae. The center’s scientific director, Lulu Skidmore, says the idea was to create a new pack animal, stronger than llama but smaller and easier to manage than camel, to transport people and goods in the desert. The center brought llamas from the United Kingdom, and one of the females was impregnated with a camel’s semen, giving birth to Rama the Cama in 1998. Although the center now has five camas, they haven’t proved to be useful. “No one uses pack animals here; everyone has cars,” Skidmore says.

Unlike sedentary camels, camas are flighty and quick on their feet; they look like oversized llamas and are missing the signature camel hump. They sport a llama-like wooly coat, which is sheered in the summertime so they don’t get too hot in the Dubai sun.

Geep

A geep is a cross between a goat and a sheep. Which of these is the real thing?

Most geeps—crosses between goats and sheep—are stillborn. Goats (genus Capra) have 60 chromosomes, while sheep (genus Ovis) have 54, making geeps too genetically dissimilar to thrive.

In 1984, scientists at the Institute of Animal Physiology in Cambridge, England, combined sheep and goat embryos to create a chimeric embryo, which contained cells from both species. Unlike hybrids, whose cells are a 50-50 mix of their mother’s and father’s DNA, geep chimeras are made up of distinct goat and sheep cells. The geep embryos were transplanted into sheep, some of which gave birth to healthy chimeras that sprouted varying patches of goat hair and sheep’s wool (wool is more crimped, fibrous, and elastic than rough goat hair).

Siedel of Colorado State University says that the two distinct cell types are able to interact together because the cells within sheep and goat organs perform almost the exact same functions. “If it’s the cells that digest food, sheep and goats have the same kinds of cells to do that,” he says.

Occasionally, a geep conceived on a farm survives—and is adorable. One such lucky geep was recently born in County Kildare, Ireland. Farmer Paddy Murphy delivered its white sheep’s baby late at night; the next day he noticed the dark calf was sporting tiny goat horns and long, lanky legs. Murphy told The Guardian he invited scientists to come to his farm to prove his rare crossbreed was indeed real.