Cute! Interesting... just had to go google that cuz I thought "card sharp" was technically correct, but everyone so commonly miss-says "card shark" that it stuck. According to grammarist.com, it's more commonly card sharp in the UK and shark in the US/Canada. I have a similar pic somewhere or our beagle, "helping" us play cards. :)
Just had this conversation with Bill. He said it was sharp; I said shark (basing my information on the 70s game show Card Sharks). I looked it up to prove I was right. Turns out we both were. Nice how that happens, huh? I think there was a Friends episode about this, too.