2. Vertebrates
• Everything up till now has been Invertebrates
– What does this mean?
• From now on all Fishes, reptiles, birds and
mammals are all Vertebrates
– What does this mean?
• Can you think of some functions of Vertebrae
that are advantageous?
– Support
– Attachment of muscles= increased movement
3. Primitive Fish (SHARK ANCESTORS)
• hagfish and lampreys
– Lack jaws and paired appendages (fins in fish)
– Lack scales and muscles (all cartilage)
Only living representatives of primitive fish
4. Class Condrichthyes
• Sharks, Skates, and Rays
– Defining characteristics
• Skeletons composed of cartilage
• Jaws
• Paired fins
• Placoid scales
5. Sharks!!!!!
• Streamlined body shape
• Heterocercal tail
• Two dorsal fins
• Paired pectoral fins
• Paired pelvic fins
– Modified in males (claspers) to transfer sperm
6. Types of Fins
• Draw the following diagram in your notes and label
the fins.
• THIS WILL BE IMPORTANT WHEN WE STUDY FISH!
7. TYPES OF TAIL FINS
• Label the diagram and draw it into your notes.
• It will be important when classifying fish!
A: heterocercal fin
B: Protocercal Fin
C: Homocercal Fin
D: Diphycercal Fin
8. Advantages to a Cartilage Skeleton
• Skeletons made of cartilage & connective tissue
– What is the difference between cartilage and bone?
• Flexible, durable
• Half the normal density of bone
– Advantages and disadvantages?
9. Why do sharks have to “just keep
swimming”?
• Lack a gas-filled swim
bladder for buoyancy like
fish
• Most sharks must swim in
order to breathe
– When sleeping: sharks pump
water over their gills
– Moving: take water in
through the mouth and over
the gills
10. Osmoregulation
• Maintain homeostasis
• Blood and tissue of sharks are usually isotonic
to marine environments
– By holding large amounts of urea in body
• Found in their urine
– If they did not have this adaptation they would
lose body water.
• Then what would happen to the shark
– Dehydrate and cells would………
» Shrink -> remember osmosis chapter?????
11. Sensory in Sharks
• Sight
– Lack eyelids
– Scientists predict that they
can see color, but what sense
is most dominant in shark?
• Smell!!!!
– 2/3 of cells in brain are used
to process sense of smell
– Can detect 1 drop of blood in
1 million parts of water
• Very intelligent!
– Exhibit curiosity and play
12. Other well adapted senses
• Lateral Line System
– Canals that run length of
body and open up to
surrounding H2O
– Used to detect
movements in water
– Can sense vibrations of
prey
• Locate prey and predators
• Fine tuned enough to feel
a heartbeat!
• Electroreception
– Feel the gravitational pull of
other bodies in the water
13. Digestion
• Teeth
– Several rows of teeth
– Fall out and are continually
replaced throughout life
• Not like ours where we
only get two sets
– Shake head to bite b/c they
cant move jaws up and
down to chew
– Food is swallowed whole
– Mouth ->stomach-> small
intestine
14. Reproduction
• Sexual, separate sexes
• Fertilization is internal
– Males transfer sperm via
claspers
– Females have ovaries
and oviduct (modified
uterus)
• Most sharks like fish lay
eggs
– Some pelagic sharks give
birth to live young!
15. Types of Reproduction
Oviparity Ovoviviparity Viviparity
(most primitive) (most advanced)
• Eggs laid outside • Eggs hatch in • Babies get milk
body mothers uterus directly from mother
• Protective case • Nutrients stored in • Live young
attaches to sea floor egg
• Smaller bc limited • Single pup
nutrients
• Whale Sharks • Horn shark • Hammerhead
• Basking Sharks • Great White • bull sharks
16. Skates and Rays characteristics
• Flattened bodies shape
– Suited for bottom living
• Always exception = manta
ray
– Enlarged pectoral fins
attached to head
– Reduced dorsal and caudal
fins
– Eyes and spiracles on top
of head
– Lack of anal fin
– Specialized teeth for
crushing prey
17. Differences between skates and rays
• Skates • Rays
– Small fins on tail – Venomous barb or
– Swim by creating a wave spines
and starts at head then – Swim by moving fins up
ripples down rest of and down (like a bird)
body – Ovoviviparous
– oviparous
