Butler anthropomorphizes T'Gatoi, whose alien body might initially feel foreign and inhuman to a reader.
T'Gatoi whipped her three meters of body off her couch, toward the door, and out at full speed. She had bones—ribs, a long spine, a skull, four sets of limb bones per segment. But when she moved that way, twisting, hurling herself into controlled falls, landing running, she seemed not only boneless, but aquatic—something swimming through air as though it were water. I loved watching her move.
Butler uses words familiar to the reader as referencing parts of the human body. T'Gatoi and the other Tlic have a "spine," "skill," and "ribs," just as Terrans and other humans do. The Tlic are also able to speak and communicate like Terrans, establishing bonds and community alongside them. These human features shared by both the Terrans and the Tlic anthropomorphize T'Gatoi and the rest of her species by assigning familiar body structures and habits to their insectile bodies.
However, the audience is still reminded of the Tlics' alien natures. T'Gatoi has "four sets of limb bones" and "swim[s] through air as though it were water." These are foreign characteristics of the Tlic that distinguish them from Terrans. The contrast between familiar body parts and unfamiliar ones reflects the nature of Gan's relationship with T'Gatoi and the other Tlic—both comfortable and unsettling.