Board Thread:Naruto Discussions/@comment-24837927-20140421121126/@comment-1512913-20140428102807

They were shown bleeding, so they have blood. "Chakra contsturcts" refers to the fact that they were made from chakra, that doesn't mean they are just chakra tho. Shadow Clones are just chakra temporarily transformed into physical form, but they dispel when harmed. The Tailed Beasts do not dispel, they can even die, hence their flesh is a real flesh.