Embed Size (px)
Citation preview
Fish Schooling
“Never let schooling interfere with your education….”(apologies to Mark Twain)
not all fish aggregations are schools
aggregation: group created by the attractiveness of some feature of the environment.
Schooling
www.seafriends.org.nz
www.blackchampagne.com
www.blackchampagne.com
not all fish aggregations are schools
aggregation: group created by the attractiveness of some feature of the environment.
shoal: group of fish remaining together for social reasons
Schooling
www.seafriends.org.nz
www.blackchampagne.com
not all fish aggregations are schools
aggregation: group created by the attractiveness of some feature of the environment.
shoal: group of fish remaining together for social reasonsschool: polarized, synchronized shoal of fish that
swim together in the same direction, at a similar speed, with a similar distance between one another
Schooling
www.seafriends.org.nz
school shoal
who?25% of fish shoal throughout lives50% shoal at some point in lives
Schooling
shape ( highly variable)fast-traveling schools = wedge-shapedfeeding schools = circular
minimum size for effectiveness as predation defensemaximum limit for effective coordinated movement
Schooling
how?primarily visual cues, as schools often break up at nightoptomotor reaction - explains prevalence of vertical bars
Schooling
how?primarily visual cues, as schools often break up at nightoptomotor reaction - explains prevalence of vertical bars
Tank exps. with vertical bars….
Schooling
why?reduced risk of
predation
Schooling
“dilution” effect - predators only get strays
why?reduced risk of
predation
Schooling
“dilution” effect - predators only get strays
“confusion” effect- flash expansion
why?reduced risk of predation
“dilution” effect - predators only get strays“confusion effect" for predators
“flash expansion”traveling: increased hydrodynamic efficiency?
usually similar in size
Schooling
why?reduced risk of predation
“dilution” effect - predators only get strays“confusion effect" for predators
“flash expansion”traveling: increased hydrodynamic efficiency?
usually similar in sizeincreased efficiency of food finding
schooling to round up preyshoaling to optimize finding food
- fish follow those that are most successful
Schooling
why?reduced risk of predation
“dilution” effect - predators only get strays“confusion effect" for predators
“flash expansion”traveling: increased hydrodynamic efficiency?
usually similar in sizeincreased efficiency of food findingincreased reproductive success
minimal sexual segregation in schooling speciesconsensus on where to go for spawning
Schooling
Why not? group feeding dictated by productivity of environment
when food is scarce, feeding is solitary
when risk of disease/parasite transmission is high
Schooling
Pitcher 1983
