Sthenoteuthis pteropus, also known as the orangeback flying squid or orangeback squid, is a species of cephalopod in the family Ommastrephidae. It is native to tropical parts of the Atlantic Ocean where it is found to depths of about . Description Like other squid, Sthenoteuthis pteropus is bilaterally symmetrical and has a head with a pair of eyes, eight arms and two tentacles and a fleshy, muscular body known as the mantle. The head is not retractable, the arms have blunt tips and there is a marked crest on the outer surface of the third pair. The tentacles are slender and the terminal sections are armed with a transverse row of large toothed suckers and other smaller suckers for capturing prey, and the column with a fixing apparatus of knobs and small suckers. The mantle is cylindrical, narrowing slightly towards the posterior end where there is a wide, roughly diamond-shaped fin. There are a number of bioluminescent photophores on the head, mantle and fourth arms, with a concentrated patch on the anterior dorsal surface of the mantle forming a luminous orange oval shape. Sthenoteuthis pteropus grows to a mantle length of about with a fin width about three quarters of this. Distribution and habitat Sthenoteuthis pteropus is native to the tropical Atlantic Ocean with a range between about 35°N and 36°S and a rather more restricted breeding range that extends to about 22° on either side of the equator. It is a common epipelagic species and is found in the upper surface layers of the sea to a depth of . Biology Squid can move fast through the water by jet propulsion, expelling a jet of water through a flexible siphon located on the ventral surface just behind the head. Some species can even launch themselves out of the water and move rapidly through air, remaining airborne for several metres. The phenomenon has been little studied because it happens so rarely and so unexpectedly, but it has been photographed on a small number of occasions, and Sthenoteuthis pteropus has sometimes tentatively been identified. The squid seems to be engaging in an active flying process rather than a passive glide as the fin is spread widely and the arms are held in such a position as might help provide lift. The squid were found to travel five times as fast in air as in water and it is thought that the