[ He places the tribble in a box, in which he has gathered several others. Don't worry, there's room.
Then he leans over and angles the tricorder toward her. ]
The tricorder is currently set to scan for biological life forms within its range. The readings are displayed on the screen. Each life form has a unique biological signature detected by the tricorder. Yours is displayed here - [ and he points ] - whereas the signals of the tribbles are displayed here. [ And of course, points in turn. And, of course, he doesn't have one. ]
The position is displayed as well as the type of lifeform. A combination of factors such as vital signs, body temperature, and even the chemical makeup of the lifeform are taken into account in order to accurately identify it.