Gasterosteiformes /ɡæstɪˈrɒstiːɪfɔːrmiːz/ is an order of ray-finned fishes that includes the sticklebacks and relatives. In the Gasterosteiformes, the pelvic girdle is never attached to the cleithra directly, and the , orbitosphenoid, and bones are absent. The body is often partly or completely covered with dermal plates. The name "Gasterosteiformes" means "bone-bellies". It is derived from Ancient Greek gaster (γαστήρ; "stomach", "abdomen") + ostoun (ὀστοῦν; "bone"). The ending for fish orders "-formes" is derived from Latin and indicates "of similar form".