Swarm 207874 225697621 2008-07-14T23:25:46Z Jwinius 141528 /* See also */ Corr: Boid => Boids {{about|swarms in biology}} {{Redirect|Schooling|the concept related to teaching|education}} [[Image:School of reef fish at Rapture Reef, French Frigate Shoals.jpg|thumb|300px|right|Shoal of the colorful [[squirrelfish]] ''Sargocentron xantherythrum'' at the Rapture Reef, [[French Frigate Shoals]].]] The term '''swarm''' ('''shoaling''', '''swarming''' or '''flocking''') is applied to [[fish]], [[insect]]s, [[bird]]s and microorganisms, such as bacteria, and describes a behavior of an [[aggregation]] ([[Wiktionary:school|school]]) of [[animal]]s of similar size and body orientation, generally cruising in the same direction. [[Group size measures|Group size]] is a major aspect of the social environment of participants. [[Swarming (honey bee)|Swarming of honey bee]]s is a more specific term, referring to the [[reproductive]] action of an entire [[Colony (biology)|colony]] of [[bee]]s (as opposed to the reproduction of single bees); see [[Queen bee]] and [[Honey bee life cycle]]. ==Fish== [[Image:Heringsschwarm.gif|left|thumb|Underwater video (looping) of a shoal of [[Atlantic herring]] ''Clupea harengus'' on its migration to their spawning grounds in the [[Baltic Sea]]. With such high speed they can migrate over thousands of kilometers. Some scientists are of the opinion that cruising in a close group minimizes energy consumption, one fish utilizing the pressure field created by the next fish. In the [[North Atlantic]], herring cruise between [[Norway]] and [[Greenland]] every year.]] '''Shoal''' can describe any group of fish, including mixed-species groups, reserving "school" for more closely knit groups of the same species swimming in a highly synchronized and polarized manner. Fish derive many benefits from shoaling behaviour including defense against predators (through better predator detection and by diluting the chance of capture), enhanced [[foraging]] success, and higher success in finding a mate. It is also likely that fish benefit from shoal membership through increased [[hydrodynamic]] efficiency. [[Image:Synchropredation.gif|thumb|200px|Juvenile herring hunt in shoals for very alert and evasive [[copepod]]s : The copepods can sense with their [[Antenna (biology)|antennae]] the pressure-wave of the approaching herring and react with a fast escape jump. The length of the jump is quite consistent. The fish arrange themselves in a grid of this characteristic jumplength. The copepods can dart about 80 times before they tire out. It takes 60 milliseconds to spread out the antennae again, and this time slot is used by the herring to finally snap a copepod. A lone juvenile herring would never be able to catch a large copepod ("Synchropredation" &mdash; results from ''in situ'' videos taken from the [[ATOLL (oceanography)|ATOLL]] laboratory).]] Fish use many traits to choose shoalmates. Generally they prefer larger shoals, shoalmates of their own species, shoalmates similar in size and appearance to themselves, healthy fish, and kin (when recognized). The "oddity effect" posits that any shoal member that stands out in appearance will be preferentially targeted by predators. This may explain why fish prefer to shoal with individuals that resemble them. The oddity effect would thus tend to homogenize shoals. One puzzling aspect of shoal selection is how a fish can choose to join a shoal of animals similar to themselves, given that it cannot know its own appearance. Experiments with [[zebrafish]] have shown that shoal preference is a learned ability, not innate. A zebrafish tends to associate with shoals that resemble shoals in which it was reared (that is, a form of [[imprinting (psychology)|imprinting]]). Other open questions of shoaling behaviour include identifying which individuals are responsible for the direction of shoal movement. In the case of [[Fish migration|migratory]] movement, most members of a shoal seem to know where they are going. In the case of foraging behaviour, ethologist [[Stephan Reebs]], writing in the journal Animal Behaviour, reported that captive shoals of [[golden shiner]] (a kind of [[minnow]]) were led by a small number of experienced individuals who knew when and where food was available.<ref>Reebs, S.G. 2000. Can a minority of informed leaders determine the foraging movements of a fish shoal? Animal Behaviour 59: 403-409.</ref> ==Quotes== [[Image:Fishes Mada.JPG|thumb|200px|Shoal of [[Silver moony]] at [[Madagascar]]]] * "One of the most striking behaviours of a shoal is its synchronization. Hundreds of small fish glide in unison, more like a single organism than a collection of individuals" [[Hiro-Sato Niwa]], [[Journal of Theoretical Biology]], 1996: 181,p 47 ==Examples== This is a partial list of animals that swarm. *[[Ant]]s *[[Bird]]s *[[Eel]]s *[[Grasshopper]]s ([[Locust]]s) *[[Honey bee]]s *[[Termite]]s == See also == * [[Boids]] * [[Herd]] * [[Swarm Intelligence]] * [[Flocking (behavior)]] ==External links== [http://www.nytimes.com/2007/11/13/science/13traff.html?ei=5087&em=&en=2770422853e9f63e&ex=1195102800&pagewanted=print New York times article on investigations into swarming] [http://pages.cpsc.ucalgary.ca/~jacob/HomeCJ/Christian%27s%20Home%20Page/Home.html Christian Jacob, Ph.D - swarm computer simulation] [http://pages.cpsc.ucalgary.ca/~jacob/HomeCJ/Christian%27s%20Home%20Page/In%20the%20Media/9A605A6F-4D85-4C9F-9CD3-FBD9949A08CC.html Lessons from Mother Nature on How to Manage Traffic - Daily Planet on Discovery Channel] ==References== {{reflist}} [[Category:Zoology]] [[Category:Behavior]] [[Category:Periodic phenomena]] [[Category:Aquatic ecology]] [[Category:Fisheries]] [[da:Sværm]] [[de:Schwarmfisch]] [[es:Enjambre]] [[fr:Essaim]] [[hr:Jato]] [[nl:School (vissen)]] [[pl:Ławica ryb]] [[pt:Cardume]] [[ru:Стая]] [[simple:Swarm]] [[sl:Jata]] [[sv:Svärm]]