About flying fish, probably even heard those who have never been to the sea. But flying fish are not the only marine inhabitants capable of planning a flight above the surface of the water. Some squid are able to fly, the cephalopod molluscs belonging to the subclass Coleoidea. Flying over the surface of the water, representatives of at least six genera of squid belonging to two families were observed: Ommastrephes, Ornithoteuthis, Sthenoteuthis, Illex and Todarodes from the family Ommastrephidae and Onychoteuthis from the family Onychoteuthidae.
The fact that some squid can fly, sailors and fishermen knew, apparently, even in ancient times. The ability to fly even found expression in the names of some squid. Thus, the species Todarodes sagittatus in English is called the “European flying squid”, and Todarodes pacificus is the “Japanese flying squid”. True, in the Russian names of these squid associations with the flight there – they are called “squid-arrow” and “Pacific squid,” respectively. But, strangely enough, zoologists practically did not pay attention to the flight of squid to the famous expedition of Tour Heyerdahl on the raft of Kon-Tiki. During this voyage, the travelers encountered flying squid (some of them even flew to the raft), and this meeting aroused the interest of researchers in behavior,
Understand how exactly squid fly, helped to monitor our main character – the squid Ommastrephes bartramii. In order to fly out of the water, the squid moves diagonally to the surface and accelerates, forcefully pushing water out of the mantle cavity through the funnel. At the same time, the mollusc moves its tail forward, its head backwards – this is the main way for rapid movement of cephalopods. Having flown out of the water, the squid spreads its tail fin, and, most importantly, bends its arch with an arch – pulls in special membranes between them. For a long time it was believed that these squids were needed by squid only for catching prey, but it turned out that for planning too. Due to the wide fin at the caudal end of the body (in the flight it turns out to be the front end) and the squashed arms on the arms, the squid actually gets two wide wings at the anterior and posterior ends of the body.
Squids can fly over the water a few tens of meters. Sometimes they fly in small groups, and sometimes whole flocks, consisting of hundreds of individuals, rise into the air. Some photographs show that a squirt of water stretches behind squid – they continue to throw it out of the mantle cavity and during the flight. The researchers suggest that this allows them to further accelerate in the air. However, when the received impulse ends, the squid can no longer accelerate and fall. Before that, they fold the fins and dive the sharp end of the body forward, immediately plunging deep enough under the water. Their flight (however, like the flight of flying fish) is not characterized by maneuverability: if the ship is ahead, the squid can not avoid a collision and often fly to the decks and even to the portholes.
Initially biologists believed that the flight needed squid to rescue from predators and even from fishing nets. But it is possible that sometimes squid simply saves energy – in fact the density of air is much less than the density of water, and in the long migrations that these animals make, the periodic use of the air medium can be fully justified.
Fly only relatively small squid, up to half a meter long – mostly young and small adults. Apparently, larger squid is already too heavy to fly.
Photo © Harold Moses from flickr.com .
Flight of squid, “Science and Life”, No. 8, 1982.