FISH

• Osteichthy• Bony fish• 20,000 species• Big →Little species• All aquatic habitats• Cold blooded• Scales and mucus• Gills

• Chondrichthy• Cartilage fish• 1,000 species• Same• Same• Same• Same• Same

Hydrolagus colleiChimaera

Fish

• Osteichthy• Cannot close eye• External

Fertilization• External

Development

• Chondrichthy• Some have eyelids• INTERNAL

fertilization• Development

SOMETIMES External

Fish

• Osteichthy• Caudal Fin =

Homocercal• Swim Bladder = YES• Neutrally Buoyant• 1 Row of teeth• Teeth permanent• Scales grow back

• Chondrichthy• Caudal Fin =

HETEROcercal• Swim Bladder = NO• Negatively Buoyant• Many rows of teeth• Teeth replaceable• Scales do NOT grow

back

Battle against Negative Buoyancy• Cartilage is lighter than Bone (negatively

buoyant but LESS sinking).

• Body shape helps give them “lift”.

• Caudal fin Heterocercal

Battle against Negative Buoyancy

• #1 Caudal fin Heterocercal

• #2 Pectoral fins like?????

Battle against Negative Buoyancy• #1 Caudal fin Heterocercal

• #2 Pectoral fins like?????

Battle against Negative Buoyancy• #1 Caudal fin Heterocercal

• #2 Pectoral fins like Airplane wings

• #3 Liver is 25% of body weight

Battle against Negative Buoyancy

• SO….

• Cartilage is lighter than Bone +• Caudal fin Heterocercal +

• Pectoral fins like Airplane wings +• Liver is 25% of body weight =

Neutral Buoyancy?????

Chondrichthys are

NEGATIVELY BUOYANT

Carcharias taurus

Hearing

• 0.5 miles away. (10 football fields)

• Hear struggling animals.

• Better than humans

Smell

• 1 drop in 25 gallons or 1 ppm.

• Openings to nose can locate exact direction of scent.

• Better than humans

Lateral Line

• Allows them to “feel” movements.

• Better than humans

Vision

• Eyes very important.• Some sharks can cover their eyes while

attacking food, with a Nictitating Membrane.• Great white shark can roll eye back into head for

protection.• Sharks vision 10X better than a cat in darkness.

• Better than humans

Ampullae of Lorenzini

• Detect electromagnetic impulses.

• Living organisms give off electromagnetic signals.

• Heart beating, muscle twitching, etc

• Better than humans

SEX

Chondrichthyes

• Internal Fertilization

Courtship (may the best male win!)

Chondrichthyes• Development ( a bit more tricky!)

• 3 different ways:

Oviparous

• Shark lays eggs in the water and leaves.

• No parental care.

• No added parental nourishment or protection.

Viviparous

• Female gives birth to live young.

• Baby sharks are attached to mother by placenta (nourishment)

• Advantage—greater protection (pre-birth)

• If babies are larger, then less babies.

Ovoviviparous

• Babies are in egg cases, but eggs are carried by mother.

• No added nourishment given.

• Advantage: added protection from external eggs.

Carcharias taurus

(Survival of the Fittest)

Intrauterine Cannabilism

Or

Oophagy

SHARKATTACKS

450 species total

447 chocolate labs

3 pit bulls

Annually, between 100 Million and 200 Million sharks are

killed worldwide just for their Fins.