Writing claw

The writing claw can refer to the claw of the digit next to the inner thumb of the forepaw, or to the entire digit analogous to a human's index finger.

A yinrih's writing claw is shaped like the nib of a fountain pen, and acts more or less like one as well. However, while a fountain pen uses capillary action and gravity to cause a "controlled leak" to produce ink flow, a yinrih has voluntary control over the muscles in the ink sac. By contracting these muscles, and by gently pressing the tip of the claw against a writing surface, ink can flow out. This mechanism allows the writing claw to work in microgravity.