Sharks

Classification Kingdom Animalia – Phylum _____________ Class _____________ – Subclass _____________ » Superorder _____________ Known as “__________” until the 16 th 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

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 _____________ __________________