SharksRead pages 155-159 & 174-177
See also: http://www.flmnh.ufl.edu/fish/education/questions/basics.html
Types of Fishes – Where Do Sharks Fit In?
• Three types: Jawless, Cartilaginous, & Bony
• Sharks fall into the Cartilaginous category– Primitive fishes– No true bones, only
cartilage– Related to skates and rays– Most are harmless– See the model in C114
Shark Diversity• The smallest shark is a
deepwater dogfish (adults are about 8
inches long)
• The largest shark is the whale shark
(a planktivore)
• The fastest shark is the shortfin mako
(swims up to 20 mph)(Note: Average person
swims about 3 mph)
http://dsc.discovery.com/videos/ultimate-guide-to-sharks-the-many-species-of-sharks.html
Shark Bodies• Notice that sharks are fish and obtain
oxygen from the water through their gills-usually 5 – 7 gills
Shark Bodies Cont.
Lost teeth are replaced in a
“conveyor belt” system, with back teeth
moving forward to
replace lost ones
Shark Bodies Cont.• Placoid Scales – sharp-edged scales can injure
prey; gives shark skin a sandpaper-like feel
• Liver – very fatty; helps shark maintain buoyancy
• Tail-upper lobe is usually longer for better power & thrust
• Usually two dorsal fins, paired pectoral fins
Shark Reproduction• Fertilization
is internal
• Males use claspers to insert sperm into female’s cloaca
Shark Reproduction Cont.• Some sharks are
Oviparous (lay an egg-mermaids’ purse)
• Some sharks are Ovoviviparous (have an egg that develops inside female-sometimes eating siblings!)
• Rarely, sharks can be Viviparous (Live-bearers-like mammals)
http://dsc.discovery.com/videos/ultimate-guide-to-sharks-how-are-sharks-born-take-a-look.html
Shark CamouflageCountershading –
darker on dorsal surface to blend with the deeper water or
the sea bottom & lighter on ventral
surface to blend with lighter colored surface waters,
making it difficult for both predators & prey
to see a shark
Shark Trouble• Most sharks need to force water over gills to
breathe, and can “drown” when trapped in nets
• Skin, oil, and fins are overharvested to the point of near extinction for some species
• PSA aimed at stopping these practices: http://
www.youtube.com/watch?v=fkxoRPv4ugE&playnext=1&list=PLB4E6B7A755C66293
Additional Shark Links• More on the importance of sharks in
healthy oceans: http://www.youtube.com/watch?v=xVKrwsXvC0A&feature=autoplay&list=PLB4E6B7A755C66293&index=5&playnext=2
• Clearinghouse of all known Shark links: http://www.postmodern.com/~fi/sharklinks/links.htm
• More general shark information: http://www.youtube.com/watch?v=xVKrwsXvC0A&feature=autoplay&list=PLB4E6B7A755C66293&index=5&playnext=2
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