Transcript Fish - Moses Classroom

Fish
North American Wildlife
Lets study some fish
• Ichthyology- The scientific study of
fish
• More then 30,000 species
• Types of fish
– Osteichthyes- bony fish
– Chondrichthyes- cartilaginous fish
– Agnatha- jawless fish
Importance of fish in the ecosystem
• Fish form an important part of the food web
in aquatic ecosystem, and can be either top
predators, intermediate herbivores, or
plankton eaters.
• A variety of birds and other animals depend
upon fish as their primary food source.
• The presence or absence of individual
species, as well as overall fish numbers can
be an indicator of ecosystem health and can
affect water clarity and water quality.
• Fisheries form an important resource for food
and recreation for humans as well.
http://www.wblcd.org/Sciencefornowakezoneinmarsh.pdf
Basic Fish Info
• Ectotherms- exist at or near the
temperature of their surroundings
• No legs instead fins
• No lungs instead gills
• Scales
• We eat them sometimes
• We keep them as pets sometimes
Biological Magnification
• Have any of you ever heard that fish contain
mercury???
• What is it? An increase in the concentration
of a substance that occurs in the food chain
• As we move up food chain more mass has to
be consumed to get same energy
• Chemicals, like DDT or mercury, that have
been polluted into waters, accumulate at
higher levels on the food chain.
• Who is at the top of the food chain?
• What fish should we avoid?
Fish Food
• Extremely important as a food source for
humans
• High in Omega 3 Fatty Acids- good for heart
• 14%-16% of animal protein consumed
worldwide
• Over 1 billion people rely on fish as their
primary animal protein
• Among the most common food allergies
• Over-fishing can cause a collapse in the food
chain
Egg laying
• 97% of fish are oviparous- eggs
develop outside the mothers body
• Normally fertilization occurs outside
body (exceptions- some sharks, rays,
and skates)
• Spawn- when a female deposits her
eggs or roe
• Male will then fertilize by discharging
milt or sperm
Schooling
• Many fish of the same species moving
in harmonious patterns
• Safety in numbers
• Not to be confused with a shoal- any
aggregate group of fish (variety of
species)
• Both benefit group members