Nature's full of clawed animals, but the frogs' defense mechanism is unique in the natural world because their claws literally rip through the skin when extended. They're also made of bone instead of keratin (sorry, no adamantium claws are known to exist in reality, except for this guy). Researchers aren't sure if the claws are retractable or not, and as Yong notes, they may never really want to find out:

The clawed frogs belong to a family called Arthroleptidae that were discovered in Central Africa more than a century ago. At first, people wondered if the claws just stuck through the skin as a side effect of the preservation process. Alternatively, the frogs may have used them to grip or climb. Their true function as defensive weapons only became clear when naturalists first described actually picking up and handling live animals.

Doing so is a mistake, and anyone who makes it is punished with a series of deep, bleeding wounds inflicted by the struggling animal as it kicks out violently with its claws. The ability is well known to the people of Cameroon, who only ever hunt the frogs with machetes or spears.

In the X-Men movie, Wolverine, when asked if it hurts to pops his claws, answers, "Every time." One can't help but think that the same is true for the frogs.
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However, many amphibians have extraordinary healing abilities that can even regenerate severed limbs. It may be that the clawed frogs, like their comic-book counterpart, have a 'healing factor' that closes up the wounds that open every time their claws are used.

Source: Not Exactly Rocket Science

He said:

I'd have to have you do it for me, because it's really hard to get in and out of this thing. There's a zipper in the back, so I guess I'd have to just rip everything off and destroy my expensive suit here that I've spent a lot of time and effort on.

Jackman says he's a fan of the Wolverine character, "... like everyone else. That's why I keep holding on to the character." He promises that Wolverine's arch-nemesis Sabretooth and the anti-mutant zealot William Stryker will both play a huge role in the film. The plot? A younger Wolverine "discovers the world of mutants and, ultimately, the ominous Weapon X program, which turns people into living weapons." Weapon X already played a fair part in X-Men 2 He also lets us know that there will be both familiar mutants and new faces in the film, including some big cameo roles.

The only question is, do you really want every facet of Wolverine and every dark secret exposed on film? We've already seen flashbacks of Wolvie geting injected with adamantium, we know he was part of a government project, and we know he's a rebel and a loner. Do we really need a whole film to tell us why? We'd prefer a film that follows the storyline from the comics where Magneto pulls all the metal out of his body, and it nearly kills Logan. Later, during a Danger Room training sequence, he discovers he has bone underneath those claws. First Look: Gavin Hood's X-Men Origins: Wolverine [First Showing]

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