Though it rarely occurs in nature, individuals from different but closely related species do occasionally mate. The result is a biological hybrid — an offspring that shares traits from both parent species. Other hybrids, which occur as a result of human intervention, are often created to obtain the best characteristics of both animals, but may have deleterious effects. Here are 10 unusual but truly unique hybrids.

1 of 10 Ligers AkulininaOlga / Shutterstock Ligers are the cross of a male lion and a female tiger, and they are the largest of all living cats and felines. Their massive size may be a result of imprinted genes which are not fully expressed in their parents, but are left unchecked when the two different species mate. Some female ligers can grow to 10 feet in length and weigh more than 700 pounds. Since lions and tigers in the wild occupy different habitats, ligers do not occur naturally. Ligers are distinct from tigons, which come from a female lion and male tiger.

2 of 10 Zebroids Peter Etchells / Shutterstock A zebroid is the offspring of a cross between a zebra and any other equine, usually a horse or a donkey. There are zorses, zonkeys, zonies, and a host of other combinations. Zebroids are bred to get the best from both species. Zebras are less susceptible to disease than horses, while domesticated horses are easier to train. They are also an interesting example of hybrids bred from species that have a radically different number of chromosomes. For instance, horses have 64 chromosomes and zebras have between 32 and 46 (depending on species).

3 of 10 Grolar Bears Corradox / Wikimedia Commons / CC BY-SA 3.0 The offspring of a grizzly bear and a polar bear, a grolar bear is unlike many other hybrid animals in that they are known to occur naturally in the wild. The first reported grolar bear sighting occurred in Canada in 2006. It's likely that climate change, which has had a profound impact in the Arctic, has caused a change of habitat for polar bears, which has resulted in the mating of these two species.

4 of 10 Wholphins Mark Interrante / Flickr / CC BY SA 2.0 A cross between a false killer whale and an Atlantic bottlenose dolphin, wholphins are hybrids that exist in captivity and may exist in the wild. The first wholphin, the offspring of a bottlenose dolphin mother and a false killerwhale father, was born in 1985. In 2005, that wholphin, Kekaimalu, gave birth to a calf, Kawili Kai, that is three-quarters dolphin and one-quarter killer whale. These two are in captivity are at Sea Life Park in Hawaii. The wholphin's size, color, and shape are a blend of the parent species; as are the number of teeth they have: a bottlenose has 88 teeth, a false killer whale has 44 teeth, and a wholphin has 66.

5 of 10 Savannah Cats Jason Douglas / Wikimedia Commons / Public Domain Savannah cats are the name given to the offspring of a domestic cat and an African serval, a medium-sized, large-eared wild cat. After the first breeding, the hybrid cats are bred again in order to call the resulting hybrid domestic. Savannah cats display a variety of temperaments, from friendly and social to shy and withdrawn. Most are reported to be able to jump as high as eight feet. In 2001, The International Cat Association accepted the Savannah as a new registered breed, and in 2012 it was accepted for Championship status.

6 of 10 Camas Photographer Craig Wright / Getty Images A cama is a hybrid of two animals from different worlds — camels from Asia and llamas from South America. The two species exhibit many differences, but camels and llamas are both camelids descended from a common ancestor that evolved in North America during the Palaeogene period. Breeding of camels and llamas, via artificial insemination, has been most successful with female llamas and male camels. The goal was to produce an animal with the size and strength of the camel and the more cooperative temperament of the llama. Camas, which don’t possess the hump of camels, are smaller than camels, but larger and stronger than llamas.

7 of 10 Beefalo Mark Spearman / Flickr / CC BY 2.0 Beefalo are the fertile offspring of domestic cattle and American bison. Crosses also exist between domestic cattle and European bison (zubrons), and yaks (yakows). Developed in the 1970s in California, the beefalo was created to combine the best characteristics of both animals with an eye toward improved beef production. Beefalo, which are three-eighths bison and five-eighths domestic cattle, are USDA recognized as a breed.

8 of 10 Geep Shown here is a sheep–goat hybrid, the offspring of a sheep and a goat. They are not to be confused with sheep–goat chimera, which are artificially created by combining the embryos of a goat and a sheep. Judgefloro / Wikimedia Commons / CC by SA 4.0 This cross between a sheep and a goat, sometimes called a geep, is rare because goats and sheep each belong to a different genus. Though matings between the two are known to occur, the offspring is most often stillborn. Live births have occurred, the most famous of which happened in Botswana in 2000.

9 of 10 Mules and Hinnies Penny Higgins / Flickr / CC BY-SA 2.0 Perhaps the most widespread and useful of hybrids are mules (from a male donkey and a female horse) and hinnies (from a male horse and a female donkey). Reputed for their hard work and strength despite their medium size, mules are dependable and often exhibit higher intelligence than their purebred parents. All male mules and most female mules are infertile, so their continued existence depends entirely on human intervention.