Bizarre Toad With Extra Leg That Looks Like Giant Tail Evades Capture

Once again, Australia has proved that it really does have the strangest animals in the world. One resident has taken pictures of a toad with five legs hopping around his backyard.

Michael Messenger, from Ipswich in Queensland, Australia, was sitting in his yard when the strange creature emerged from the bushes.

"It was normal size, but smaller than a hand," Messenger told Newsweek. "It just hopped at a normal toad speed."

five legged toad
The five-legged toad as photographed by Michael Messenger. The toad has a condition known as polymelia. Michael Messenger

"It had an extra part. It just looked like a normal toad, except it had a leg as a tail," Messenger told ABC News Australia. "I don't think [the extra leg] has any function. It just drags behind, but it looks weird."

Extra limbs are caused by a birth defect called polymelia. This often arises from a genetic defect in the growing fetus, which leads to abnormal cell division and growth. Occasionally, one of a pair of conjoined twins may be absorbed into the other. Some of its limbs are left attached to the remaining fetus. And sometimes, if a fetus is damaged physically or by chemical influence, the development of the limbs can be altered.

There are various forms of polymelia: cephalomelia, pyromelia, thoracomelia and notomelia. These are classified depending on where the extra limbs are growing from, such as from the head, pelvis, thorax and backbone, respectively.

This condition is occasionally seen in animals, and in very rare cases, in humans. One 2002 study by the universities of Bern and Zurich in Switzerland estimated that only four out of every 100,000 cattle born worldwide have additional limbs.

"I have seen toads with five legs before. It's very rare," toad researcher Rick Shine, from Macquarie University in Sydney, Australia, told ABC News.

"In the course of research, we've handled many thousands of toads. I've probably seen it two or three times myself."

In this case, Shine said that the toad had been injured when it was a tadpole, causing one of the limbs to develop into two.

"While it's an embryo, the limb bud could get split into two and end up producing two legs," Shine said. "It's something that happens with frogs more often.

"Other animals have babies in utero or in eggs so they're protected, but tadpoles aren't. The tadpole is swimming around in the open, and usually one parasite attacks the tadpole and injures the limb bud, and you end up with two legs."

Bullfrogs in the western U.S. have been seen to develop extra limbs because of infection by the flatworm parasite Ribeiroia ondatrae. This larva burrows into the tadpole, forming cysts around the frog's developing limbs and altering their development.

While these extra limbs aren't usually dangerous to the animal, they can hinder its mobility. This makes them more vulnerable to predators.

"It is likely to be having difficulty with leaps and bounds because they rely on their powerful leg muscles for it," Edward Narayan told 9NEWS. He is a senior lecturer in animal science from the School of Agriculture and Food Sciences at the University of Queensland, Australia.

Messenger tried to catch the strange amphibian, but to no avail. The toad bounded back off into the wild, despite its extra limb.

"It always disappeared when I went to get a bag," Messenger said.

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