Upload
leeanna-cota
View
2.339
Download
2
Tags:
Embed Size (px)
Citation preview
Class Chondrichthyes: Skeleton made of cartilage
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
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
Class Condrichthyes
• Sharks, Skates, and Rays– Defining characteristics
• Skeletons composed of cartilage • Jaws• Paired fins• Placoid scales
Sharks!!!!!• Streamlined body shape• Heterocercal tail• Two dorsal fins• Paired pectoral fins• Paired pelvic fins
– Modified in males (claspers) to transfer sperm
Types of Fins
• Draw the following diagram in your notes and label the fins.
• THIS WILL BE IMPORTANT WHEN WE STUDY FISH!
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
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?
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
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?????
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
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
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
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!
Oviparity(most primitive)
Ovoviviparity Viviparity (most advanced)
• Eggs laid outside body• Protective case attaches to sea floor• Smaller bc limited nutrients
• Eggs hatch in mothers uterus • Nutrients stored in egg• Single pup
• Babies get milk directly from mother • Live young
• Whale Sharks• Basking Sharks
• Horn shark • Great White
• Hammerhead • bull sharks
Types of Reproduction
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
Differences between skates and rays
• Skates– Small fins on tail– Swim by creating a wave
and starts at head then ripples down rest of body
– oviparous
• Rays– Venomous barb or
spines– Swim by moving fins up
and down (like a bird)– Ovoviviparous