Sharks

Classification• Kingdom Animalia–Phylum _____________• Class _____________–Subclass _____________

»Superorder _____________

• Known as “__________” until the 16th century–Name “shark” may have come from the

Yucatec Maya

Evolution• Earliest sharks evolved _________ years ago• Today – _________ species– Smallest – dwarf lanternshark (7 in)– Largest – whale shark (largest fish – 40 ft)

Skeleton• No bones–Use cartilage and connective tissue• Strong , but ___ the __________ of bone– Reduces weight saves energy

–Cartilage may be _____________• “bone-like”

–No functional _____________•Must stay in water

Jaw

• Covered in a layer of _____________–Complex ________ surface• Single tile in a mosiac

– Tiny hexagonal plates• Crystal blocks of _____________

–Most sharks have one layer of tesserae• Great white sharks – up to _____________

Teeth• Embedded into _____ rather than the jaw• Arranged into _____ rows of ______ teeth–Continuously replaced • Gums “_____________” them to the front• Can shed ____________ teeth in a lifetime

• Tooth characteristics determined by _______• Very important to fossil record – all that

remains

Tooth Anatomy

Fins• Supported by unsegmented _____ composed

of _____________

Tail (Caudal) Fins

• ____ different designs found in sharks– Shapes evolved due to different _________

and _____________–All are _____________ in design• Top is _______ than the

bottom

http://upload.wikimedia.org/wikipedia/commons/d/d6/Shark_Tail_shapes.svg

Buoyancy• ____ swim bladder• Large _____________–Up to _____ of body mass–Contain _____________• Oil that is _____________ that water• Sharks hunted for this oil–Put in capsules as a health supplement–Used in vaccines–Also available from plant sources

Respiration

• Oxygen removed as water passes through the mouth and over the _____________–Process known as _____________•Most sharks can pump water over their

gills while at rest–Some cannot (obligate ram ventilators)

–Gills _______ covered (as with most fish)

Circulation

• Sharks have a ______ chambered heart

_________________• Most sharks are _________________ (cold

blooded)–Body temp is that of the environment

• Family Lamnidae sharks can raise their body temp higher than the water temp (includes mako and great white)–_____________– Strip of red muscle in center of body attached

to the __________________ (miraculous net)

Rete Mirabile• Uses ___________________ flow design

_____________

• Living in salt water• Large production of _____ – Shark’s tissues ________________ (in balance

with) the sea water• So, few sharks can live in fresh water– Bull sharks can change their kidney function to

____________________________

Senses – Smell• Very keen ________ sense–Can detect __________

of blood in sea water– Even greater attraction

to chemicals found in _________ of organisms• Leads sharks to

sewage outfalls

Olfactory Bulbs (in pink)

Senses – Sight• Eyes similar to most vertebrates–Well adapted to the dark marine

environment• Use a _______________ (bright tapestry)–Reflects light back through the retina

to increase amount of useable light–Humans do the same (_____________

in a photo)–Can _____________ and _____________ their

pupils

Senses – Sight• Sharks have eyelids, but _____________–Water cleanses eyes

• Use __________________________–_______________ that moves over eyes to

protect them during ___________ on prey

Senses – Hearing

• May be able to hear prey ____________ away–Hard to test

• Small opening on each side of the head– Leads to the inner ear

• Sense _________________ among the water molecules

Senses – Hearing

• _____________ system– System of _________ within the lateral line• Runs the length of the body• ___________ expose water to the system• Contains ____________ cells with hair-

like projections• Also helps with ________ and movement

Lateralis System

Senses – _____________• Sharks can detect electromagnetic fields

produced by all living organisms– Sharks have the _____________ electrical

sensitivity of any organism–Helps them find prey (even under the sand)–Use ____________________________• Electrorecptor organs–Hundreds to thousands per shark

Pores (on a tiger shark)

Senses – Electroreception

• Ocean currents travel through the magnetic field of the earth–Creates electric fields•May allow sharks to _____________ the

world’s oceans• Allows sharks to detect _____________

__________________

http://upload.wikimedia.org/wikipedia/commons/8/88/Electroreceptors_in_a_sharks_head.svg