From an email response posted to Baen's Bar BuShips dated August 11, 2004:

Treecat toenails

    About those treecat toenails... Why are they so short, and if they're that short, how do they do the damage that they do?

     

    I suppose I should properly have said that treecat claws are [12.7] millimeters long, rather than 1 centimeter long. I actually intended it to be understood that they were close to a half-inch in length, and I simply rounded down, which I shouldn't have done. This is still short, by the standards of terrestrial cats, but treecat claws are not really close analogues to terrestrial felines' claws. Treecat claws are needle-pointed and sharply curved. The concave, rear-facing side of the claw also closely resembles an extremely sharp knife. Although treecats often use their claws when climbing, they seldom extend them fully when doing so. I have made repeated reference to the fact that they have long, agile, slender, etc., fingers, which they normally use much more as a monkey or a chimpanzee might when climbing. They are, however, capable of extending their claws in order to climb in a fashion much more similar to a terrestrial cat. It's important to remember, however, that they are called treecats because humans familiar with terrestrial cats were looking for a convenient referent to hang on them. And, of course, the original name was bestowed by a very young -- if exceptionally bright -- girl, not a trained xenobiologist. A treecat's claws evolved primarily as weapons, not as a general utility adaptation, and they are not composed of the same materials as terrestrial felines' or canines' claws/toenails. I haven't made a study of exactly how cats and dogs claws and toenails differ from one another, but my understanding is that a cat's claws are basically bone, and a dog's are basically specialized, toughened skin. Treecat's claws are much closer in composition to what we might think of as teeth. That's not exactly accurate, of course. For one thing -- although this hasn't been particularly emphasized or dealt with in the novels to date (I'm sort of saving a lot of details about treecat physiology and societal organization for the series I want to do centered around Stephanie Harrington) -- the "bone" used by Sphinxian critters is substantially heavier and denser than that of terrestrial animals, thanks to several factors, but most of all to the fact that all of these Sphinxian animals are adapted to a heavier native gravity. Treecat claws should not be confused with toenails, as I think the above establishes, since they are actually much more similar in appearance and hardness to human tooth enamel. Moreover, treecat claws are like shark's teeth in two ways. First, they have the same sort of "slicing" sharpness. Second, like shark's teeth, they regrow quickly and can be regrown as many times as necessary. In terms of just how sharp they are, in both the needle and the knife edge sense, you might want to reflect upon the fact that the reinforced portion of Honor's garments is literally "bulletproof."