The remoras (remora pronounced /rəˈmɔːrə/ or /ˈrɛmərə/), sometimes called suckerfish, are a family (Echeneidae) of ray-finned fish in the order Perciformes. They grow to 7–75 cm (2.8 in–2 ft 5.5 in) long, and their distinctive first dorsal fins take the form of a modified oval, sucker-like organ with slat-like structures that open and close to create suction and take a firm hold against the skin of larger marine animals. By sliding backward, the remora can increase the suction, or it can release itself by swimming forward. Remoras sometimes attach to small boats. They swim well on their own, with a sinuous, or curved, motion.