Sharks and RaysSharks and Rays

Class Chondrichythes Class Chondrichythes

Common Rays in Common Rays in HawaiiHawaii

Fish vs. SharksFish vs. Sharks

Sharks are Fish!....ButSharks are Fish!....But

Do not have bonesDo not have bones 5-7 external gill 5-7 external gill

openingsopenings No gill coverNo gill cover No swim bladderNo swim bladder Internal fertilization Internal fertilization

with clasperswith claspers Placoid scalesPlacoid scales

Form and FunctionForm and Function

Heterocercal tail = upper lobe longer Heterocercal tail = upper lobe longer than the lowerthan the lower– Strengthen and support tail for forward Strengthen and support tail for forward

thrustthrust

Teeth in rowsTeeth in rows– Teeth lack roots and often breakTeeth lack roots and often break– Easily replacedEasily replaced

Placoid scalesPlacoid scales– Reduce drag, protectionReduce drag, protection

Paired Pectoral FinsPaired Pectoral Fins– Airplane wings, provide liftAirplane wings, provide lift

Predominant dorsal finPredominant dorsal fin– BalanceBalance

Shark’s SEVEN SensesShark’s SEVEN Senses S – SoundS – Sound

Can hear a fish 100 yards awayCan hear a fish 100 yards away

O – OlfactionO – Olfaction In one nostril and out the otherIn one nostril and out the other

L – Lateral LineL – Lateral Line V – VisionV – Vision E – ElectroreceptionE – Electroreception T – TouchT – Touch T - TasteT - Taste

ElectroreceptionElectroreception

Similar to a metal detectorSimilar to a metal detector Ampullae of LorenziniAmpullae of Lorenzini

– Detects the magnetic field around Detects the magnetic field around living organismsliving organisms

Only other animals with this Only other animals with this sense: duck billed platypus and sense: duck billed platypus and spiny anteaterspiny anteater

Sharks in HawaiiSharks in Hawaii

Aggressive SpeciesAggressive Species

Tiger – 18 ftTiger – 18 ft Galapagos – 10-12 ftGalapagos – 10-12 ft Hammerhead - 12-15 ftHammerhead - 12-15 ft Great WhiteGreat White

Other SpeciesOther Species Blacktip – 8 ftBlacktip – 8 ft Reef Black Tip – 6 ftReef Black Tip – 6 ft Reef White Tip – 6 ftReef White Tip – 6 ft Sandbar - 5-6 ftSandbar - 5-6 ft

Shark AttacksShark Attacks never swim alonenever swim alone don't swim with open wounds or speared fishdon't swim with open wounds or speared fish don't swim erratically or make splashing don't swim erratically or make splashing

noisesnoises avoid the water at night - sharks hunt at avoid the water at night - sharks hunt at

nightnight avoid murky water - sharks may mistake you avoid murky water - sharks may mistake you

for a preyfor a prey don't harass or provoke sharksdon't harass or provoke sharks if you witness fish behaving erratically, leave if you witness fish behaving erratically, leave

areaarea if you encounter a shark, remain calm and if you encounter a shark, remain calm and

slowly leave areaslowly leave area

Environmental Environmental ConcernsConcerns

Sharks are top Sharks are top predatorspredators

““Keystone Keystone species” that species” that keep prey keep prey populations populations under controlunder control

Sharks extinct?Sharks extinct? Populations Populations

continue to continue to declinedecline

If fishing If fishing continues, continues, could go could go extinctextinct

18 species are 18 species are threatened with threatened with extinctionextinction

Our Impact…Our Impact…

Something to Think Something to Think About…About…

~ 6 people killed ~ 6 people killed by sharks a yearby sharks a year

~ 12 million ~ 12 million sharks killed by sharks killed by humanshumans

– BycatchBycatch– FisheriesFisheries

Basic Fish Fin Basic Fish Fin FunctionsFunctions

Dorsal fin - stability in swimmingDorsal fin - stability in swimming Pelvic fin - stability in swimmingPelvic fin - stability in swimming Caudal fin - main propelling finCaudal fin - main propelling fin Anal fin - stability in swimmingAnal fin - stability in swimming Pectoral fins - Locomotion and side Pectoral fins - Locomotion and side

to side/ back forth movement.to side/ back forth movement.