In terms of cryptozoology—the study of “hidden” or as of yet undiscovered animal species—the chupacabra occupies a special place due to the wide range of its sightings and the varied nature of its description. The name itself even sets it apart from most other questionable creatures of the dark: Chupacabra literally means “goat sucker” in Spanish; sightings of the creature are often accompanied by dead farm animals that have had all, or nearly all. the blood sucked from their bodies. But as sightings of this creature increased over the last twenty-five years, it turned out there were actually two different creatures named chupacabra.

Or maybe it was the same creature and it somehow evolved?

The story of the chupacabra begins in the remote areas of the Puerto Rican highlands in 1995. It was during that year when farmers began finding their prized goats dead and drained of all blood. The only evidence that pointed toward anything were two puncture marks left on the animals’ necks, which looked eerily like something out of a vampire movie.

Word of the attacks began to spread and finally sightings of the goat suckers were reported. The chupacabra was described as a bipedal creature, about four to five feet tall, with scaly skin, a head that resembles that of a “gray alien,” and long, claw-like fingers. Numerous sightings of the scary creature were reported around Puerto Rico and then in other Latin American countries throughout the 1990s, but by the early 2000s the sightings began to evolve.

Goats, chickens, and other domestic animals were still being found drained of all their blood in a number of different Latin American locations, but there were less and less reports of bipedal creatures to go along with the attacks. Instead, witnesses began reporting vicious looking canine creatures.

People began regularly sighting the new chupacabras north of the Rio Grande River.

Theories about the newer chupacabra sightings ran the gamut from logical to absurd: Some argued that the creatures sighted were probably just sick coyotes, while others thought the chupacabras were a new hybrid species, or worse, a science experiment gone wrong that had escaped from a lab.

Finally, by the late 2000s, chupacabra corpses began turning up in Texas that could be professionally tested in labs. All of the tests revealed that the chupacabras were either domestic dogs, coyotes, wolves, or a mixture of the three. Experts believe that the bizarre appearance of the creatures is primarily the result of mange or other infections.

Nothing otherworldly.

As for the reports of farm animals drained of all blood … well, experts have pointed out that in most cases this was exaggerated. They say that the animals lost plenty of blood, but that it was all caused by predators feeding on them. Other experts have pointed out that when mammals die the blood goes to the extremities, giving the impression that they no longer have blood.

And how did the chupacabra evolve from a bipedal creature to a canine?

Well, the original cases in Puerto Rico began with a single eyewitness. Her testimony got front-page newspaper attention in the American commonwealth and became an urban legend in the early days of the World Wide Web. So, skeptics believe that the mystery of the chupacabra has been solved.

Or has it?

Some point out that mange doesn’t explain all of the mutated-looking canines found in Texas, and they suggest that they are possibly a new species created by continued crossbreeding between coyotes and domestic dogs. The logical explanations also don’t necessarily explain how most of the farm animals were killed. Though not all of their blood was sucked out, the dead animals weren’t eaten in typical canine fashion.

These unanswered questions have led some to conclude that although the original Puerto Rican chupacabra sightings were probably a hoax, the later ones were based on valid creature sightings that were/are possibly a hybrid canine species.