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Sharks and Rays Class Chondrichythes
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Common Rays in Hawaii
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Fish vs. Sharks
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Sharks are Fish!....But Do not have bones 5-7 external gill openings
No gill cover No swim bladder Internal fertilization with claspers Placoid scales
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Form and Function Heterocercal tail = upper lobe longer than the lower
Strengthen and support tail for forward thrust Teeth in rows Teeth lack roots and often break Easily replaced
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Predominant dorsal fin
Placoid scales Reduce drag, protection Paired Pectoral Fins Airplane wings, provide lift Predominant dorsal fin Balance
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Shark’s SEVEN Senses S – Sound O – Olfaction L – Lateral Line
Can hear a fish 100 yards away O – Olfaction In one nostril and out the other L – Lateral Line V – Vision E – Electroreception T – Touch T - Taste
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Electroreception Similar to a metal detector Ampullae of Lorenzini
Detects the magnetic field around living organisms Only other animals with this sense: duck billed platypus and spiny anteater
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Sharks in Hawaii Aggressive Species Tiger – 18 ft Galapagos – 10-12 ft
Hammerhead ft Great White
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Other Species Blacktip – 8 ft Reef Black Tip – 6 ft Reef White Tip – 6 ft Sandbar ft
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Shark Attacks never swim alone
don't swim with open wounds or speared fish don't swim erratically or make splashing noises avoid the water at night - sharks hunt at night avoid murky water - sharks may mistake you for a prey don't harass or provoke sharks if you witness fish behaving erratically, leave area if you encounter a shark, remain calm and slowly leave area
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Environmental Concerns
Sharks are top predators “Keystone species” that keep prey populations under control
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Sharks extinct? Populations continue to decline
If fishing continues, could go extinct 18 species are threatened with extinction
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Our Impact…
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Something to Think About…
~ 6 people killed by sharks a year ~ 12 million sharks killed by humans Bycatch Fisheries
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Basic Fish Fin Functions
Dorsal fin - stability in swimming Pelvic fin - stability in swimming Caudal fin - main propelling fin Anal fin - stability in swimming Pectoral fins - Locomotion and side to side/ back forth movement.
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