Slimy Japanese giant salamanders can bite off your finger The Japanese giant salamander can grow up to 5 feet long, weigh 80 pounds and can easily bite off a large chunk of your finger in a split second. The slimy, mottled amphibians have remained virtually unchanged for millions of years. Once hunted for food, the salamanders are protected as a national treasure in Japan and efforts are underway to breed the threatened species in captivity, according to National Geographic. The salamanders are rarely seen, coming out only at night to lurk in cool streams around mountains and foothills. "Knowing how giant salamanders go about breeding and what conditions are necessary for that to happen comes in useful when considering how best to protect them in the wild," Tim Johnson, a Tokyo-based salamander enthusiast who has observed these creatures in the mountains told National Geographic. The way rivers have been modified in recent decades has made it difficult, and sometimes impossible, for them to migrate upstream to breed. After many attempts to breed, a male named Daigoro and a female called Sachiko finally managed to conceive and 500 eggs were fertilized. While their parents may find their newborns cute once they arrive, the rest of the world won't. Japanese giant salamanders are included in our list of the world's 31 ugliest creatures. Click here to see the rest of nature's horrors.