From the boiler room of the human imagination have arisen a myriad of strange animal concoctions, welded together from parts of animals, humans, and plants. From jackalopes to Batboy the tabloid legend, from the Sphinx to Frankenstein to genetically modified foods, whether crafted in literature or created in material form, hybrids are precarious creatures, abnormal, aberrant, and potentially unstable. The repugnance or titillation aroused by composite creatures stems from their ability to rupture normally autonomous categories. Hybrids either represent the fruitful violation of the natural laws segregating species (species are interbreeding groups reproductively isolated from other groups), or they blur together the three kingdoms of nature (humans, animals, and plants), or, more disturbing still, hybrids confuse the distinction between the productions of humans and the productions of nature. Like the Minotaur, born from the unholy lust of a woman for a bull, hybrids represent human fears of disorganisation arising from unnatural and unlawful mixture.
From ancient times, composite animals have been the stuff of myths and travellers’ legends. Hybrid creatures were part of an alternate reality, distant in time or space and, therefore, were symbols of all that was foreign, fearsome, or mythical. Some creatures possessed unnatural abilities like Pegasus, the flying horse, or Griffins, flying lions with the heads and wings of eagles. Some creatures were malevolent and enjoyed intoxicating powers over unwary humans with the misfortune to encounter them. With the head of a woman and the body of a bird, Sirens lured sailors to their deaths on the rocky shore of their island with the irresistible charm of their voices. Others like mermaids and fur-bearing fish were exotic but not inherently dangerous. Some creatures were simply outlandish. The Barnacle goose was thought to grow from a tree, and the Tartary or vegetable Lamb grew from a small shrub to which it was attached by the navel. Its meat apparently tasted of fish and its blood of honey.
image: the Tartary Lamb from Sir Hans Sloane's enormous collection of natural artefacts. Sloane's collection was donated to the state and eventually became the British Museum, from which the Natural History Museum eventually splintered off. The image, as you can read, is taken from the website of the Natural History Museum in London.
Fraudulent animals do not occur naturally - they are human creations. While mutant forms do regularly occur in the natural world without human intervention (check out monstrous births, under Dabbling in Wonders), they are mother nature's playful mistakes rather than intentionally created, fraudulent beasts.